Actually . . . I just checked my config and I am running approx 251Mb of video memory with a 1366x768 resolution which should accept almost any rendering. I would suggest that you check your DirectX version and your video memory. Although Civ4 BTS says thatyou only need 64Mb of video memory . . . you really do need double that at least to handle the graphics. That's my experience at least
forgive the dumb question, but how do I check my config?