Same problem here on the same sort of machine (G4/933 with Nvidia MX4 with 64MB).
The cursor is fine, though, on my TiPB (G4/800 with ATI RageM7(?) with 32MB).
I tried various mice/drivers to see if anything would help but no luck (Logitech MX700 with its own latest drivers or USB Overdrive, then the standard Apple mouse with only its own drivers active).
Fortunately, no other apparent effects on graphics or gameplay, so more of just an annoyance rather than a show-stopper.