Look as much as Mac OS X just destroys windows in almost every aspect, game developers right 90% of games for windows only. To be able to play Crysis, CoD4, even steam (crossover, it works but meh, why pay $40). Just install windows. You won't even notice its installed. Just always boot into Mac OS X, then when u wanna play games, hold down Alt/Option and click windows. Then set it to reboot into mac os x when your done. Thats what I do at least.
Or you can just compile wine from source and it's free!