get riva tuner and make sure all the pipelines are turned on. I know this should be done already with a GT but those look like the scores i got with my plain old 6800.
I don't use profiles meself, so could just be speculating, but you aren't accidently using an nVidia profile with these benchmark programs are you? A profile with aa turned on or something?
did you remember to install your nforce 3 drivers, I forgot to one time after installing windows and thats about where my scores sat if I remember right,
also how far did you over clock your card? when I pushed mine to far it would start to loose points in 3dmark