StingingVelvet: One problem is that while the PS3 has more exclusives the 3rd party games on it are generally worse versions than on Xbox. For example if you want Red Dead Redemption, which you should, the PS3 versions runs at a lower resolution with a worse framerate and more pop-in. It's up to you how much you care of course.
inc09nito: Yes, this makes me think a bit, because I've read similiar stuff a few times. I guess it differs from game to game, but in overall my feeling is that (theoretically) XBox versions are performing better.
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The tricky part for me is that you guys mentioned a lot of games I don't actually know. And that's good, but I need some more reading to make up my mind.
Put in mind 2 things... Exclusives .. Live functionality - PSN is free(PS + is not) & Xbox Live Gold is 60$ a year. Good exlusives on both consoles... but more AAA exclusive for PS3.
Test the gamepads ...some people prefer the Dual Shock...some the Xbox pad.
Put in mind the price diff too...
Xbox 360 250 GB - £149.95
PS3 160 GB - £189.00