Multiple Video Cards?

[Jimmy the Greek]

Is it possible to use two video cards in one system? I have an old 3DFX PCI card lying around that I would like to use specifically for late 90s-era games that are glitchy in D3D mode, and was wondering if it can be used as a secondary card to my AGP Radeon card.

Can this be done, with output from both cards being viewable through the same display?