I would say marginal difference between a "Pro" card and a gamer card. MoI uses DirectX (Direct 3D) for display acceleration, Pro gpu's strength typically lies in the OpenGL drivers and are optimized as such. Gamer cards strength is in D3D since that is what games use. I would recomend the best gamer card you can (reasonably) afford. Both ATI (AMD) and nVidia are good and there are fans on both sides.
Windows 7 x64, Precision T3400, Intel C2Q @ 3 GHz
8 GB RAM, ATi Radeon HD 3870 |