to be honest, in terms of hardware, its whether you wanna pay now or pay later.
the ps3 comes with everything, right out of the box.
the 360 is cheaper, but it doesnt come with all the things that a system needs.
i.e. wifi adapter: $100, HD-DVD drive (very much optional, but if you want to watch "nexgen" movies, you kinda need it) $200, if you want online for five years, that's another $250
i like the ps3 better, and the library is getting very good very fast.
for the record, i dont own either... but im thinking about getting a ps3.