63.4 and 5887 are good enough scores for a 9800 Pro. With a 6600GT you would see more like 90-100FPS D3 and 7500 with 3DMark, I'll guess. Try Counter Strike Source Stress test and Aquamark 3D for more proof of performance.
For more system performance max out your RAM timings and try Omegadrivers.net for great ATI drivers.
I think Anandtech reccomended the Albatron 6600 GT for OC'ng and cooling.