Looks like my video card is dying on me. It's an Asus V9520 64MB AGP and is only 2 years old. I can't run any of the 3D tests using dxdiag.exe, and simply trying to preview a 3D Windows screen saver gives me the following:
What would cause a video card to do this? I take it I should just buy a new video card?

What would cause a video card to do this? I take it I should just buy a new video card?