Has anyone here upgraded from the 8800GT to the new 4870? Do you notice a big difference in gaming or is it only slightly better? Also, I'd like to mention that I do not want to boot into Windows to play games. I play the Mac version of Call of Duty 4 and I'm curious what others have to say about the game performance with the 4870. I did look at barefeat's benchmarks but, I like to know what the real world has to say instead of relying on time demo tests with Anti-Aliasing on and stuff.