This subject comes up from time to time so I thought I would just add my two cents worth and save hopefully some from the pain.
When selecting a new computer to use for CAD, Video, or Graphics editing use, please do not just select the default graphics cards (GPU) listed by the computer manufacturer. In most cases the default graphics card is the cheapest and definitely not intended for heavy graphics usage. Most default cards are tuned for regular business applications or video gaming. While video gaming can be demanding on a video card, it does not require the same requirements as CAD or graphics applications like full OpenGL support. Most gaming cards like the NVIDIA GeForce from NVIDIA support only a subset of OpenGL as well as some other limits that do not impact usage for general usage or gaming but definitely affect your performance and stability when using them in CAD. NVIDIA will tell you the only graphics card line that is designed for CAD are the Quadro line as the Geforce is only for general use and gaming. Many other vendors will provide their supported application groups on their web sites.
Some software vendors will also provide a list of tested cards such as the Autodesk Inventor or Discreet 3DS Max teams. This is a very extensive effort as not only do the graphics cards change quite frequently but so do their drivers.
Most people I know when specifying a new computer look primarily at the CPU, RAM and hard drive but more and more these days the graphics card is as important as the CPU. In fact in the future with the next Microsoft Windows operating system code named Longhorn, the GPU handles much more of the computing than in prior releases of Windows making the graphics card quality even more important.
My personal rule of thumb is that if the graphics card manufacture is a virtual unknown or the card is under US$100 then I am making a dangerous gamble. Most of the high performance cards are above US$200 which may seem expensive but compare that to the slower performance, instability, and other support issues and the $200 is a very cheap investment and cheaper than most current hard drives.
A Shaan Analogy Alert: When buying a high performance race car, you should not go cheap on the engine. You cannot select low cost 4 cylinder alternative to the high performance 8 cylinder engine, and still realistically expect to win or even finish a race.
Don’t try to save money on the graphics card as it will come back to haunt you in performance, stability and image quality all of which are extremely important to those using CAD.