Blammo - Have you upped your monitor refresh rate? Changed mine from 70 to 100HZ and it helped my frame rate quite a bit. I guess the simple reason for this is it gives your monitor and graphics card more times per second to match(sync) and display data.
Also tried 600X800 resolution...frame rates shot up to 80 to 122...but looked like crap on 21 inch monitor.
New Nvidea driver 1 april 2004 - think you said yiou had that but not sure.
Hope this helps, sorry if already covered - but it helped me,
Sytstem specs,
Athlon 64 2 Ghz
NVidea 5950 ultra
1 gig pc 3200 ram
Windows XP home edition
DSL connection