well ive been checking out some forums about it, and people are saying you need 1 gig to get it to run smoothly on high. if you dont mind knocking it down to medium or low, 512 would do you fine. the box says 256 min, but 512-1024 is recomended. i wont know for sure till i pick it up, but i do know the demo ran pretty badly until i upgraded to a gig.
i also read somewhere that it doesnt like ATI cards, but i think thats probalby some Nvidia fanboy who saw that it said "Optimized for Nvidia" on the box and bought into the marketing.