What makes a system good is primarily the library for it. Once upon a time the PS3 was a clear winner. But then, third party developers said to themselves, "oh shit if we develop PS3 exclusives we'll lose money" and then the PS3 became a lot less significant. Still good, but not as great. If the game library was roughly the same, I'd PROBABLY go with the PS3 myself, because I rarely play console games online and dislike console FPS games. The wii is an exception to this as FPS games are fantastic on the wii, but I don't like playing FPS games with a joystick. The thing about the 360/XBox is that a large portion of the game library involves guns. Mostly FPS/TPS games. I haven't actually played the 360 myself and only last week touched the PS3 for the first time.
From what I've heard/observed, I'd prefer the PS3 for a number of reasons. One, I'm familiar with the control scheme/controller setup. Two, if you move the 360 console while it's on, it destroys the disc inside it. Note that this is a weak argument against the 360 because let's face it, how often do you move the console while it's on? Not very often. Three, I don't know how the wireless controllers work on the 360 but they're done quite well on the PS3. They take at most half an hour to charge up (you can use the controller while it's charging; you'll just be stuck on a cord for a bit) and from there you get 10 to 15 hours of wireless play before you need to recharge.
I haven't gotten either a 360 or a PS3 yet, because I'm a huge KH nerd and I'm just going to buy whichever console KH3 is launching for (last I checked Squenix had "not decided" yet). I'm really hoping it's a PS3 title because I don't think Disgaea3 is being ported to the 360 and Disgaea is easily among the greatest series' I have ever played.
tl;dr/actually on topic:
Consider which genre/methods of play you prefer the most. 360 is easily the leader in online console play, not that I play console games online myself, but if that's your thing, you're probably better off with a 360. 360 favours shooters and other action-oriented games of that type, whereas PS3 is probably going to be more prone to Action/Adventure/RPG type games, and is likely to have greater single-player enjoyment. The major downside to the PS3 right now is that it still doesn't really have a good selection of games yet.
Back to personal banter:
The 360 has quite a few games I'd like to play that have been released (such as Beautiful Katamari and Dead Rising) whereas for the PS3, the only released game I have any interest in is Heavenly Sword, which I have actually played through and completed (and the acting, both voice and model, is quite superb).
Back on topic:
Since you don't own any consoles at the moment, I'd really consider the backwards compatibility issue. The PS3 earns huge points for me, here. The XBox was good as a console, but in my opinion had a horrible library of generic games. The PS2, on the other hand, is probably my favourite console. If you count the DS as a console, then it counts as competition with the PS2, but DS aside, the PS2 is easily my favourite. It has a huge library of excellent games, and an even greater library of crap I don't care about. Plus, it's very easy to play games for free on it =3 you just need access to games (a rental store/friends in your case as 1GB/mth bandwidth sucks mooseballs for piracy), a DVD burner, and a 30 dollar DVD package. Stealing aside, however, the PS2 is still one of the strongest consoles ever released.
If you want to go to a semantics/morality standpoint (who does, really?) sony has, since their PS2 era of glory, become absolute douchebags. Microsoft is still barbaric and money-hungry as they've always been, but they are now being out-asshole'd by Sony, hardcore. If you're worried that buying a PS3 might send the message that you support companies being tyranical douchebags, you might want to take that into account.
EDIT: oh also happy belated birthday, dood
