both have pros and cons. with the ps3, you can store all your media files on the hard drive through usb, cd, and through the network. the 360 won't let you store files locally, unless they are ripped from an audio cd or from the marketplace.
both can stream files fine, but the 360 is more consistent with file types. divx is a bit of a hit and miss on the ps3, some work and some don't. and of course the obvious, music can not be played whilst in-game on the ps3, whilst the 360 does it no problem.
both can play:
divx
wmv
mp4
mpg
mp3
aac and wma
ps3 can also play:
atrac
avc
if you don't mind streaming from your network or playing from a usb device or cd, then 360 is the way to go.
if you want to store everything on the actual console, and don't mind converting a few files, then ps3 is the way to go.
