Well... one word of caution though, if you are getting one of those new intel mac mini's (which are awesome by the way
) I'm not sure if all of the games run... because lots of apps seem to crash in it. Mac's aren't exactly great for gaming and as Javester mentioned their video cards aren't that good... and you might also need more memory (depending on which one you get) to play the game smoothly. Although the other day I was trying out the Atari emulator... but then I just got bored...
By the way just check out apple's site- http://www.apple.com/games/
, they've got the list.... if you're interested.
If you want to do more gaming I think you should either get xp or just get a console for playing games, it might turn out better for you.