Being a Mac user has it own advantages, but what you will lack is widely spreader PC games - like Counter-Strike or just any new Havok-powered game. Fortunately, Blizzard are Mac-fans too, so you can play any game they developed without any issue, i.e. World Of Warcraft.

Buuut... If you're an owner of new Intel-based Mac (luckily you) you can play all this gorgeous stuff freely - just boot your Mac into windows and start playing.
What about me, I bought my own Intel-Mac last week and it's wonderful! It's black MacBook and it's twice faster as my huge G5 iMac, very impressive. But when it comes to games... there is a GMA950 Intel video chipset that can't put a lot of frames per seconds to make the latest games playable. I missed like 2 years of PC-gaming after switching to my first Mac. I just wanted to ask anyone - what game will run on my MacBook just fine, I don't need a lot of polygons or shaders, that's what my Xbox 360 is for.

Counter-strike is the only game that comes to my mind now o_O

P.S. Ah, here is the photo of my MacBook... Or BlackBook, CokeBook, or just simply PreciousBook