Here's my current settings.
It's on Vista 64, though, and the DirectX seems to work much better there. I only have a 9600GTS (1GB DDR3), which I think is selling for around $120 now, but it works awesomely. 3D-Orbits are quite smooth.
I think I disabled the Texture compression for a reason, but I forget now. Ah well, it seems to be working quite well with these settings.
On our XP systems, we've been using OpenGL drivers, because the DirectX seem to behave at least 10x worse. With OpenGL on Quadro FX1500s, we've gotten performance almost comparable to what I get on my Vista + 9600GTS. But I haven't installed the latest performance drivers yet for the Quadros - I've been meaning to do that, just haven't gotten that round tuit yet.