Here are Mastercam's recommendations... out dated IMO
they state Open-GL compatible.. and I believe Nvidia Quadro is the only Open-Gl compatible card left on the market.
Which card to buy depends on what you're doing
Nvidia Line card
If you're doing simple 2d lathe and mill you could probably get by with an FX 580
the more surfacing and 5 axis work you do the more card you need.
The more card you have, the better Verify will run ... at some point, in complex / large surfacing jobs
Verify will crap out on you, no matter what hardware you're running.... but high end video cards
do help and increase your work envelope
For mid level work the new Quadro 2000 is a petty good card
We are running FX-3800's on our older work stations and Quardo 4000's on the newer ones..
The 4000 is a sweet card