ive got a PS3, and played the 360...... here's my opinion....
i am biased as ive been a sony console man/boy throughout! so PS3 all the way!
i have never liked xbox, mainly because i dont like microsoft! i didnt think the first xbox graphics where all that special compared to the PS2.
i have played on an xbox 360 in HD and it was awesome, but i have played on my PS3 with a normal tv, and i thought the graphics where better on my normal tv (playing fifa 08)
the PS3 is silent, when it starts you hear the fan for like 5 seconds, then never again.
im guessing you have already bought an xbox 360 so there isnt too much point in all the biased opinion i put in

, but the games coming out on PS3 just look mind boggling!!!!!
my sister won my PS3 in a competition, but if i was paying for a console out of my own pocket, having played both, i would of forked out the extra money for a PS3