Linux has a program available called WINE allowing your to run Windows appilcations on a Linux Box, ive seen people run Half-Life, quake 1-3, and more games.
But like the others said, be prepared for a battle, and i suggest knowing what your doing before you even INSTALL linux.
If your just gonna play games, Stick with XP...i run Theme XP, and you can make it look MUCH different than everyone else at those LAN parties.
if you REALLY wanna be different, get a pimped out case with lights and stuff.