Well I have a AMD3800 2gig Ram and a 6800GT clocked to Ultra. I can't have everything maxed but the sliders are a fair way to the right. Everything looks great and it plays smooth.
Mind you that is at 1024 x 768 atm as I only have a 17in CRT. Am getting a 20in TFT widescreen in a few weeks - might notice a drop in performance when I have to ramp up the ress. Not that it will make much difference to the interface as the menu windows remain the same size - wtf?!?!
Dude, keep the effects on, like grass and the like, for this game as it really does make a difference to the atmosphere of this game. There is nothing like being attacked by a wolf or bear you couldn't see cause of the tall grass, makes your reactions really come into play - something novel for an RPG.