I'd upgrade those drivers to the Cat 3.8's or 3.9's. Newer drivers change the 3d page in your display panel advance section.
Gives you a slider that by default is centered 50/50 quality/perf.
Your rig oughta be able to run AH balls out quality which would
be like 16x FSAA, 4x Smoothvision, Highest Quality textures and
mipmaps.