I'm sure Zing will be along later, but I always check out Tom's VGA charts (
latest AGP Chart).
The 6800GS seems to fit between the 6800 & 6800GT.
ATI wise, there is an X800 GTO and the new X1600 Pro in your price range. Not used either myself - happy with my 9800Pro. (Short review of X1600
here)