I have the ATI9600pro (as seen in my sig):
My default settings were 350/200. I have different configs which work all for me without artifacts. Here you go (incl. 3DMark03)
Performance Configuration (untweaked): 2600
Tweaked Configuration (385/220): 2834
Highly Tweaked Configuration (410/234): 3017
Ultimate Tweaked Configuration (440/250): 3227
The higher you go, the more you have to make sure that the fans aren't blocked.