I have an x1600 and I'm using the latest driver (XP).  It's ok, however, if I have too many objects in my scene, the opengl slows WAY down and I have to switch from opengl preview to software preview.

I forget what ATI driver version it is that resolves the slowdown, but I heard that you also lose some features when going to the old drivers.

You might wanna search this forum for ATI OPENGL DRIVER, that might help.

Regards,
                     CG