i have both cards, and the bmks don't seem do justice...
i don't play the games, but the kids say that the 4850 is much smoother; boosts the minimum frame rate; 'looks' better; handles AA in games where the 8800gt gets bogged...
these are subjective measurements, of course, but with the amount of time my spawn spend on the pc i have to believe that their perrceptions are valid...
8800gt sli is pretty good, though... i consolidated 2 of my 8800gt's (when i got my cheap 4850's) into a box and it sure seems like they've fixed a bunch of the scaling issues (but it's still a little problematic in some games)... awaiting the $199 q6700 to replace the 3.0ghz e4500 in that box... ought to let the gt's fly...