hhmmmmmm....PS3...for lots of options and superior graphics and Xbox for its massive online community....and its wide range of games....(PS3...Fallout 3 baybe!
I can count the number of decent games that the PS3 has on one finger. The Xbox 360 has TONS. Grand Theft Auto 4, Too Human, Mass Effect, Oblivion, Halo, just to name a few. As far as I can tell, the PS3 just has Metal Gear Solid 4. So, in my opinion, go for the 360. Even if it breaks down, Microsoft repairs it for free, and gives you a free month of Xbox Live when you get it back.