I have both, and I prefer my XBOX360 much more.
And I got mine a year ago, and I haven't got the RROD, meaning the newer Xbox's dont seem to have it.
Heres some games out at the moment for the XBOX360 which are superb:-
Devil May Cry 4
Gears of War
The Elder Scroll's IV: Oblivion
Halo 3
Mass Effect
Assassin's Creed
King Kong
Amped3
The Orange Box
And some games comming out soon which you must not miss:-
Lost Odyssey
Tom Clancys: Rainbow Six Vegas 2
Jumper: Griffins Story
Saints Row 2
Grand Theft Auto IV
Hell, I know some of them are out on PS3 aswell, but although you'll be getting the same game on each system, with XBOX360, you'll be getting Achievement Points aswell!
Each game has "achievements" on them, where you unlock them for a certain ammount of GamerPoints via doing a certain task. (ie On Gears of War theres one for completing each level + the game, collecting COG Tags, killing enough people on Online Ranked Matches with a certain weapon) and as you can see, it motivates you to do more things available in the game, because anyone on XboxLive can see how many gamerpoints you have (and Say you got 30Achievement Points on a Game, that 30 will be added to your gamerpoints). And the most Achievement Points you can get on a game is either 1000 or 1250.
XboxLive is also GREAT! You go on some games online, playing against other people, download movies, demos, games, game addons etc. And although you pay for XboxLive (its 40Pound per year) you get loads more people on XboxLive than PS3 online and also, much better gaming!
So, to me, the Xbox360 wins by far.