The ONLY reason I see for buying an Xbox 360 over a PS3 would be if more of your friends have an Xbox. The PS3 is such good deal for pretty much the same price as the Xbox360, and in the long run it actually costs less, I don't see how anyone can argue against that unless they're throwing complete bullstuff around.
And for those who say "oh no games fur ps3 get sum xbox." What the forget? Really, think more. There are plenty of amazing games for the PS3.