NFL2K5 looked better because the XBox had a much better graphic card and more power. As far as the music and video highlights, they were able to do that because the XBox came with a hard drive and the PS2 had it as an add-on that no one bought.
The PS3 and XBox360 will be very similar from a hardware standpoint. Different parts, but same results. The only difference I see is with the controller. One has motion sensors and one does not.
I really do hope the PS3 is much better because I want to justify (to myself) buying the system and selling my 360. MLB The Show will play a big factor into my decision as well