I owned a PS3, and now own a 360 elite. Overall though, i prefer the 360.
I LOVE the way the PS3 looks, what with the sleek black, and the look of the OS looks fantastic, but the xbox is alot more user-freindly.
The PS3 can be a little complicated when copying files over for the new user, yet with the xbox, you can either sync it with your computer, or just extact the files from the portable device to the xbox's harddrive.
Also, the 60gb PS3 is now out of production (60gb is best to go for imo). SO the only way your going to get it new is most likely off of ebay, which i would'nt trust. Yet xbox has the elite, which has 120gb, comes with alot of freebies like gold plated HDMi cable, headset etc. etc. and other goodies.
Power wise, there both very similiar. The PS3 is claimed to have better AA in games, yet when i play the something like GT5, it seems to me like no AA is being used. Same goes for games like virtual fighter. Yet in the xbox, i definetely notice AA being used, especially in games like mass effect or saints row.
The xbox has alot more games made specifically for that console, ones like forza 2, saints row etc.
PS3 has a couple, and i do mean a couple. Like GT, Motorstorm or resistance etc.
The PS3 can use wheels like DFP, or G25. Xbox does have wheels, which are'nt bad, but are'nt great either.
So overall, my verdict is go for the xbox. I know i may have seemed like a fanboi, but i think the xbox is better value for money, has better online, and is alot more use-freindly.