The image quality on 8xxx-nVidia-cards is slightly higher than with previous nVidias. My OCed 7800GT runs SH4 nicely, but depending on drivers self-shadowing and lighting looks pretty ugly (81.20 are the latest drivers, that support self-shadowing over larger distances. Pretty nicely shown especially in LOMAC.)
Currently, the 8800s series have a distinct advantage in speed over other cards on the market. With the upcoming 2900s series from ATI, this will very likely change dramatically, though. As said above, the quality on ATI-cards is also better.
There are also rumours that the 2900s series will be 150-200 bucks cheaper than nVidias 8800s, but will be equipped with a physics processor onboard.
