PS3 or XBOX 360?

now that im done school i wanna buy either an xbox 360 or playstation 3 but im not sure cuz the 40gb ps3 and 20 gb 360 are around the same price. I wanna buy the sytem for the gamin not for the looks. i really love racing games like gran turismo, project gotham, forza etc. i also like fifa,nba and the occasional shooting games. ohhh and things like street fighter and tekken. Which one is best for me.