There's also Linux. If we were talking about OS configurations anyway. We practically are since it's the OS that we use, not the actual box of a machine. So we'd have Windows, OSX, and Linux.
Actually it is the other way around.. On my intel based mini I can run any Mac, Linux, BSD, etc., or Windows application, seamlessly... That software line is so 1980's... come on..
You PCer's out there don't know what you are missing! I can run anything on my mac that you can on your pc. Enlighten yourself... MAC all the way. CowboyGuru
For online gamers/developers it's almost always a must to get Windows to run the latest games. Put aside the best graphic cards and you still have a game that won't be compatible with a computer because of the OS. It's a good thing the market is now catering to OSX users though.
I use a Macbook. Whenever I mention it school people scoff and say "a MAC? That doesn't even count as a computer!" People who say things like that have no idea what they're talking about. :-/