Here they are, provided this is not truncated by the forum. We shall see.
1.) Mac OS X
never crashes. Fully protected kernel.
2.) No .dll hell.
3.) No product activation of any kind.
4.) Simple install and reinstall process. (insert CD, reboot and hold down the 'c' key. Wait for the installer to come up. Select type of install [clean install (wipes drive), install.] Hit okay, agree to EULA [not very long, I might add], hit install and go get a cup of coffee.)
5.) Great
support, requires no product activation number of any sort.
6.) Galoshes of
free software thanks to Cocoa (Mac OS X/NeXT API) and simple UNIX/Linux ports (i.e. TuxRacer). Sure, there are billions of apps available for Windows but most are crap (There is no denying this. I've used half of them probably

)
7.) Safer than Windows (no security holes, less crashes (easier on your drive/system.)
8.) Can use Linux and UNIX software via recompile (and XWindows if you need a windowing interface) w/included Developer Tools.
9.) 'Drag and Drop' fully implemented in almost all apps (i.e. I can drag a file over an application's icon in the Dock [Mac version of the taskbar, better IMO. Less clutter]. If the app can read the file correctly, its icon will hilight. Release and the application will launch and open the file. Many other instances, too long to list).
10.) BBEdit, a great text editor (Unix [LF], Mac [CR], Windows [CRLF] .txt supported) and web development app, Mac only. This app understands HTML much better than any other app I've ever used, Mac or Win. I use it to clean up code made by Dreamweaver MX.
11.) Peripherals work without hassle and plug n' play works like a freaking charm. Most drivers are preinstalled. (Only loaded when needed, much like Frameworks and Extensions, so they aren't sitting in the background wasting valuable memory space and processor cycles.)
12.) You can move files even if they are open.
13.) UI is much better looking, easier on the eyes (then again, almost anything is compared to the Fisher Price GUI AKA Luna.)
14.) More logical structure to system hierarchy.
15.) Bill Gates had absolutely no part in the development and does not run the company

.
16.) Services are great (I will list an example since you probably don't know being as you don't use Mac OS X: AppleSpell AKA CoreSpelling is available to every app. System-wide spell checker [included in the TextEdit which I am typing this up in, OmniWeb [my main browser, very fast], Proteus, Fire, and Adium [3rd party AOL clients that everyone uses. (Proteus does MSN, ICQ, Jabber, and Yahoo as well.)], and just about everywhere else. The library is also system-wide so if you add a word it shows up in other apps as well. Nice underlining of misspelled words ala Microsoft Word.)
17.) Global Menubar (has clock, menu extras [PPPoE, Sound, Monitors, Airport (which is wireless networking), network, just to name a few.) Also has 'Apple Menu', from which can be opened System Preferences (one application with multiple 'panes' that you can add and sort. Very efficient compared to the Wintel method). Also, there aren't multiple menubars for every app leading to less confusion and better ease-of-use.
18.) Quartz-style antialiasing everywhere, 4 modes (sharp, smooth (default), strong, and LCD display which utilizes sub-pixel antialiasing. Very similar to font smoothing in Adobe apps and eBooks).
19.) A 'fluid' GUI which uses the same interface elements everywhere in much the same fashion, mostly due to the fact that Apple included an interface builder with the Developer Tools that allows a developer to easily conform to the Aqua GUI standards.
20.) Final Cut Pro is Mac-only and works extremely well with G4 processors. Final Cut Pro on a dual 1.25GHz PowerMac G4 is much faster than using dual Athlons and Premier.
21.) Free 'iApps', iTunes, iMovie, iDVD, iPhoto, iChat, iCal, iSync. Arguably, you can do the same things with other free utilities on the PC side, but the ease of use and integration with the operating system just isn't there.
22.) UNIX based, powerful terminal.
23.) Seamless integration over UNIX foundation, you never see the CLI unless you want to (if you want to you can start up verbose, go into single user mode in the cli and open the terminal and bust out as many shells as you want.

)
24.) No virii. Period. The only reason most Mac users have anti-virus software is to avoid giving virii to their Windows-using counterparts. There are no virii due to the fact that the system is very secure. There are trojans, however, but even these require the user to enter the root and/or superuser password, which is not enabled by default in any event.
25.) System Preferences, as mentioned before, has a very clean organization (Personal, Hardware, Internet & Network, System, Other [user installed preference panes that have not been organized by said user] and a 'Favorites' toolbar at the top where you can shove any of them.
26.) Applications aren't dependent on an open window to remain open.
27.) Spring-loaded folders (when dragging a file over a folder or drive, a user-specified delay starts. If the delay ends, the file/drive opens and user can then put file in a folder within the 'spring-loaded' folder or spring-load another folder open, etc.)
28.) Nice icons, Icon kit distributed by Apple for developers. 128x128 maximum size, 16x16 minimum size, 32-bit color, 8-bit greyscale mask (masks are used to determine the transparency of a given area of an icon, black is completely transparent, white is opaque, varying transparency with grays. System icons are excellent and informative.
29.) Friendly support and discussion communities (AppleInsider, MacNN, MacFixIt, etc.) with very knowledgeable users.
30.) Lack of Ad-Aware due to lack of spyware slowing system down.
31.) Minimize looks really cool, wait till you've seen it in person. Windows can be minimized into the Dock, the window morphs itself into an icon there via the 'genie,' 'scale,' or 'suck' techniques.
32.) Dock is simple and informative. Right click on an open app to view a list of its windows, and a few commands that can be executed in the background (examples: with iTunes i can pause/play, change to random, repeat, or normal, many other things, with Proteus (chat client) I can connect/disconnect, put on an away
MASSAGE?, start a new conversation with a user from a list, etc.). Also a quit option in that pop-up window. Hold option and it becomes force quit to get rid of inactive apps. You can also stow unopened apps there, and put files and folders to the right of the Dock. Right click on a folder in the dock, and you can hierarchicly view its contents. Trash (about the same as Recycle Bin) sits to the extreme right of the dock, and can be emptied from it. I can go on and on...but I wont cause this is already too long

.
33.) Force quit as mentioned before always works,
always. Quitting the Finder (similar to explorer in windows) doesn't end up crashing the system.
34.) Microsoft Office (v. X) is better on this side. Even they say so.
35.) You can be an ?ber-geek and kernel hacker if you want to.
36.) It isn't bloated with a bunch of Microsoft BS ala .Net and all those other crud apps. If you delete an app that came with the system it wont screw the system up.
37.) You can join the ranks of higher intellect.
38.) Things just work. Printing, Scanning, CD burning, networks, etc. all handled nicely by included system tools.
39.) Mac OS X actually allows your laptop enough battery life to be useful (~5 hours with one battery).
40.) Easy back-up and reinstallation. I wont bore you with the process but reinstallation is basically an install as mentioned earlier.
41.) The Apple Retail stores are some of the best (won many, many awards for design and functionality), and have actual knowledgeable staff. If they don't know the answer to your problem they have a direct line to Apple HQ.
42.) Drag and Drop (as mentioned earlier) of installation and deletion of applications. No .dll hell, and no registry!
43.) The [url=http;//www.apple.com/ipod]iPod[/url] now (slightly) compatible with Windows, but very well integrated into Mac OS X and iTunes. Also functions as a Firewire (IEEE 1394, Sony calls it iLink) hard drive, you can even install a Mac OS X operating system onto it and boot off of it.
44.) Disk images rock (great compression [.dmg format], in Mac OS X only the .dmg format is widely used. Also supports all forms of .img but doesn't need to since they are obsolete. You can create a disk image and use it just like another hard disk. Also when using a read-only disk image it's just like using a CD.
45.) You don't click Start to Shut Down.
46.) You don't have to OK 10 windows when you install something.
47.) You don't have to supervise your computer through the startup process.
48.) You don't have to supervise your computer through the install process of system or apps.
49.) Computer setup couldn't be easier, setup assistant is actually useful and can import settings from another OS install.
50.) One system-wide save dialog in all apps, compared to 3 or 4 with Windows.
51.) One print dialog in all apps, compared with a few thousand in Windows

.
52.) Programs use the same shortcut key combos, in Windows they are dissimilar most of the time and some apps don't even have them.
53.) When you install software/system updates you can still do other things, including multiple installs going at the same time. Browse the web while a system update downloads itself and installs. Then get another update and install that. One restart per system update/app update and sometimes no restart instead of many with some apps/system updates in Windows.
54.) Closing a window wont kill your app.
55.) Internet Explorer/Windows Explorer isn't built into the OS so if IE crashes, the whole system doesn't go down.
56.) Apple doesn't create their own (competing) standards to screw up the true standards.
57.) Applications for Mac OS X aren't as intrusive as many Apps on the wintel side, both user and system-wise.
58.) Mac OS X does not perform Illegal operations, I.E. selling pot to your neighbor at break-neck prices leaving you in debt. (Joking!)
59.) Mac OS X tells you that there is not enough disk space on a volume if that is the case
before you start copying.
60.) Great for web development (mySQL, SMB, PHP, Java, everything already integrated into the OS).
60.) Web sharing via Apache can be turned on with a few clicks (open System Preferences, open Sharing, click 'Start' button next to Web Sharing. Dump files in Sites folder of your user folder, located inside of the Users folder which is in the root of the Hard Drive.
61.) Same as above only for file sharing (SAMBA, AppleTalk, TCP/IP, whatever you want.
62.) Click a checkbox in the same pane and it puts up an FTP server.
63.) AppleScript language makes automation of Applications easy.
64.) Since the menu bar is at the top, you can just flick the mouse and you are there. Don't have to aim at individual ones in windows. Much, much faster.
65.) Mac OS X is tightly integrated into the hardware and there are few hardware conflicts because on this side, Apple controls both the operating system and hardware, and every other aspect of the Mac.
66.) You spend less time fixing your computer and doing system maintenance, and more time enjoying life.

Or whatever it is you would rather do.
67.) You don't have to reinstall the operating system when something goes horribly wrong on a periodic basis. Normal users aren't allowed to modify or delete anything that would cause the OS not to boot. The superuser, however, can do whatever.
68.) Mac OS X doesn't have a knack for doing the nasty-nasty to your hard drive, mostly because of the no-virii factor.
69.) After buying your computer, it gets faster on a regular basis (Mostly free Mac OS X updates and upgrades.).
70.) Mac OS X is customizable to an astounding degree if you have the right tools and knowledge. Even with little knowledge and little UNIX-savvyness (a person such as I), you can do any number of things to it.
71.) Extremely fast boot time. My old POS iMac [233MHz G3 proc, 66MHz sys bus and 144 pin 66MHz SO-DIMMs, 5200 RPM 4 GB HD] takes less than a minute to boot and login. That is an almost 5 year old computer running the latest OS. The newer comps are omigod awful fast

.
72.) Pre-emptive multitasking means you don't wait while your peripherals configure, your files copy, your apps open, etc. Very well threaded.
73.) Entire system takes complete advantage of multiple processors at the lowest level.
74.) Your memory is only limited to the size of your hard drive, using advanced memory management and paging. Mac OS X does not fragment disks nearly as fast as Windows does, so virtual memory is much faster. Rarely used. however, since the most active apps are given dibs on actual RAM.
75.) If you have a graphics tablet or pen-input, Mac OS X has system-wide functionality much like your Palm only better and more accurate. Anywhere you can type, you can write. A translucent sheet of 'paper' is draped over wherever you want, resizable. Trains itself to your handwriting.
76.) Mail (an app) in Mac OS X has the most advanced Junk-mail filters to date, with 3 modes (learning, another one i cant remember after it finishes learning, and a quickie that isn't customized).
77.) Bluetooth integration. Cell phones, PDA's. etc, work with iSync, iCal (a calendaring and appointment app). Absolutely seamless.
78.) Sherlock can find stock quotes, movies in your area, maps, translate stuff, lookup yellow pages, track shipments, auctions, book flights, and searches many search engines. Ad-free and quick, with a simple interface.
79.) Quartz Extreme utilizes your video card to render the interface (if the vid card is good enough, I.E. using it is faster than just letting your proc do the work) so you can watch several Dads and movies at the same time, play with all kinds of UI effects with no dropped frames or skips.
80.) Finder previews rock. Displays text of text documents, plays videos miniaturized, displays small versions of pictures (128x128 at max for videos and pics), file size, creator, extension, lots of cool stuff.
81.) The sleep functionality is better implemented than the standby mode offered by windows. Instantly comes back on, and you can leave your portable running on the battery for like a day or so

.
82.) Mac help actually works and is very intelligent and well organized. Very fast, and applications can add their on sections.
83.) Dual boot functionality is very well implemented and easy to use. In fact, as soon as I installed OS X (way back in October of last year) there was already an option to select Mac OS 9 as the boot OS.
84.) Supports something like 20 languages out of the box, and easily allows for applications to have multiple languages, which are matched to the current system language.
85.) Unlike Windows, Mac OS X uses dynamic mouse tracking (instead of linear mouse tracking). This means that if you move the mouse very slowly, the cursor moves slow on screen. Very handy in graphics apps, web development apps, and just about everything. Precise selecting. Speed up the movement of the mouse and if you want you can go across the screen in about an inch and a half of mouse movement. This also makes using small UI widgets and
what not easier to use, and in general the entire operating system is less frustrating to use because you don't have to be as precise with the mouse.
86.) Thanks to UNIX, Mac OS X is a true multiuser environment. Users can have their own set of preferences, preference panes in the system preferences, everything. Access is easily controlled via the simple yet useful Get Info window. The superuser can read, write, and execute everything.
87.) System-wide address book, containing telephone numbers, instant messenger screen names, email addresses, everything you can think of and you can add as many custom types as you want. Accessible by all apps, Address book application does not have to be open for it to be edited or used.
88.) Rendezvous, a TCP/IP utility (based on a standard being partially pioneered by Apple, open source) that allows you to find others on a network. Good uses of this are printers that configure themselves, these printers are already shipping or planed by HP, Lexmark, Epsom, possibly some others as well. No configuration. Set up a file sharing network or LAN party with absolutely NO configuration. Also, iChat will seek out users to chat with on a network with no configuration whatsoever. For more info see http;//www.noconf.org .
89.) In addition to great language support, lots of character sets (something like 2k chinese characters, I'm not sure) are included.
90.) iTunes has 'smart playlists.' These add attributes to ID3 tags of MP3 files that show how many times you have played it, and your 'user rating.' You can have playlists sort by year, artist, any ID3 tag, most played, top rated, etc.
91.) MID support out of the box, and a great MID configuration tool.
92.) Free Developer tools with every copy. 200MB installation gets you the tools of the pros at no extra cost. New distributions available at developer.apple.com
93.) Calculator in Mac OS X is scientific, and has support for those little lists like you would get from a calculator w/printing thing (can't think of the name of that ATM.)
94.) Location manager allows you to easily change any aspect of the system preferences with a snap. Create a new location, like work, and then select which things you want to save/change. Save it and boom, you can connect to dialup with your laptop at home, and to the LAN at work. Nice menu accessible from the Apple menu in every application.
95.) Full keyboard access allows you to use the operating system very effectively without a mouse, going so far as to control the pointer with the keypad. Mouse crapped out? Don't worry, just hit the option button 5 times in rapid succession and it will enable itself. Mouse your way to an online store and order yourself a new mouse.
96.) System-wide speech recognition. Usable by any app, works great if you have a good microphone.
97.) .Mac, think .NET done right. You get 100MB of web storage (disk, which mounts like any other drive) that supports php, cgi, etc, online templates, free anti-virus software (to keep your Windows-using counterparts safe

), backup software that automatically backs up your preferences and specified files to your disk. A POP/IMAP/Webmail account (
username@mac.com) with 10MB of storage, max of 10MB attachments. Online, you can create simple and good looking slide shows, resumes, movies, you name it. $50 bucks a year (about
what you would pay for the virus software anyway.)
98.) Desktop pictures can be animated, or change from once a month to every 5 secs to a diff picture. Drop a folder of pictures on the Desktop preference pane, and they will go by in a nice slide show. You can do the same thing with the screen effects Preference Pane and make a slide-show screen saver of whatever you want.
99.) Keychains, a simple service that allows users to securely store passwords and
what not from every application. A keychain can be set to unlock when the user logs in, be always unlocked, be always locked (except when opened w/user login/password), etc. Many applications make use of this service.
100.) Quicktime 6, which supports MPEG4 and AAC, and virtually every other movie, sound, and image format known to mankind. AAC is basically the quality of MP3 at half the size, as is MPEG4 with regard to video. Just released, supported first on the Mac.