I remember seeing a development video for God of War 2 for the PS2, the only way they could make each scene look so good was by culling everything that wasn't on screen at the time. Can't see that working as well for crysis' open worlds. But saying that I remember running the demo very smoothly with medium settings on an Athlon64x2 @3GHz and a 6600GT. I expect if I'd played with the settings I could have got a little more detail out of it. I think you may have hit the nail on the head, on my current setup Crysis barely uses more than 1 of my quad cores (25%) the newest version of the cryengine seems to balance things out much better hence the smoother gameplay, so if they can optimise the code well for each of the consoles architectures then it could look half decent, although not as good as it does on the PC.