Well, Athlon 64's have a theoretical bus speed around 1.6 GHz, so I'm not sure how well CPU monitors will work with them.
Always, always, always install the NVIDIA drivers on a machine with a NVIDIA videocard! The XP drivers for videocards are raw shit. NVIDIA's drivers are what makes the videocards run on games and benchmarking programs. I suggest you install the 45.23 drivers from
www.nvidia.com and run it again!
-Lasereth