Yeah played the Crysis demo (it's 1.7GB I think). I had heard it's hardware requirements were outrageous (to the extent that even with the best hardware currently available, it won't run smoothly on the highest settings) and it is. I have a Core 2 Duo E6700 (2.66GHz), 2GB low latency ram and a 1GB 7950GX2 card, so it's a beast of a system - and it wasn't even smooth with the graphics setting at their lowest. Awesome game though, but looked crap as hell on the lowest setting. Looks like I might be in for an upgrade when the holidays come around, but I'm trying to wait for the supposed GeForce 9-Series, which are apparently due out in the next couple of months. Oh, but I am attempting to run it at 1920x1200, as I have a 24" LCD, so that's a lot of the reason, I'd imagine.
The UT3 Demo plays smooth-as on my system, with all the settings maxed out, so I think Crysis is just a massive step up.
Cheers