I've got a 7900GS and it works pretty well, but I really want to get Crysis and want it to run great. I don't know if I should buy another 7900GS and run them SLi, or just shell out some cash for the 8800GT. It's supposed to be the best card out pricewise. I can't figure out how the frame rates would compare. Should I upgrade? or just run SLi?