When I asked for a 64-bit machine, I was told they would take care of me. They purchased and built a custom desktop for me and it has a 2GB graphics card. It screams in NavisWorks. I think it's a bit excessive but they didn't want to have to upgrade the graphics card at another time.

As for recommendations...you've got me. I've found working on a laptop with 128 mb integrated graphics works well on some models but can't navigate others. This beefy workstation I have now doesn't seem to have any problems with any of our models. Yet.