Depends om how demanding stuff you wanne do.
I know for other CAD programs they advice a 4xx serie or higher.
Saw this about slid works ;
Although SolidWorks is designed to work with any generic graphics card that supports Windows
(desirable resolution would be 1024x768 or higher with 32K colors or more), a graphics card with
hardware OpenGL acceleration will provide improved performance, especially in 3D model viewing
(repaints, spins, zooms and pans). Detailed info on video card support and testing is available at: http://www.solidworks.com/sw/support...rdtesting.html
Video cards designed for “gaming” or multi-media applications do NOT offer maximum performance for
SolidWorks and other 3D CAD applications. Game/multi-media cards are optimized for a low number of
polygons displayed on the screen, and a high frame rate. CAD applications have essentially the
opposite requirement, polygon count is high (all the details in your design model) and the image does
not change rapidly, so high frame rates are not as critical.