Aquamark
6600gt=54.4
6800=54.5
9800xt=47
Doom3 1024x768 no aa/af
6600gt=79
6800=80.1
9800xt=46.5
Doom3 1024x768 4xaa
6600gt=41.9
6800=52
9800xt=?
Far Cry 1600x1200 no aa/af
6600gt=39.2
6800=59.3
9800xt=40.6
Far cry 1600x1200 4xaa/8xaf
6600gt=22.4
6800=17.8
9800xt=20.5
Halo 1280x1024 noaa/ 4xaf
6600gt=49.2
6800=46.8
9800xt=36
Halo 1600x1200 no aa/8xaf
6600gt=35.7
6800=35.1
9800xt=24.3
Jedi Knight 1280x1024 no aa/af
6600gt=86
6800=93.3
9800xt=66
Jedi Knight 1600x1200 no aa/af
6600gt=66.4
6800=77.7
9800xt=53.7
jedi knight 1280x1024 4xaa/8xaf
6600gt=37.6
6800=75.8
9800xt=41
JEdi knight 1600x1200 4xaa/8xaf
6600gt=20.6
6800=55.3
9800xt=33.6
UT2004 1280x1024 no aa/af
6600gt=52.5
6800=56.7
9800xt=51.6
UT2004 1600x1200 no aa/af
6600gt=42.8
6800=47.5
9800xt=38
UT2004 1280x1024 4xaa/8xaf
6600gt=34.4
6800=27.9
9800xt=31.3
UT2004 1600x1200 4xaa/8xaf
6600gt=22.6
6800=19.4
9800xt=23.5
So you can see that the 9800 xt and 6600gt are similar. The 6600gt might have a little edge and the 6800 has an edge over the 9800xt and the 6600gt.
i got the benchmarks from
http://www.anandtech.com/video...oc.aspx?i=2196&p=1