Also picked up GoW:CS. there is a VERY noticeable difference visually with the HD. Had my PS3 and PS2 playing GoW 1. Flipped back and forth (different inputs on TV) a couple times to see the difference. Gotta say, I remember playing on the ps2 and being like "damn, this is a good looking game!" Now... we getting spoiled XD
Oh and as others have noted, the PSP games are not on a disk but on a code voucher.