FiringSquad have an interesting article documenting the rise and fall of 3DFX, from an insider prospective. Their server isn't too reponsive for me right now (being Slashdotted doesn't help), but the article is worth the read if you want to know what happened to the company who had so much to offer.

While all this was developing, NVIDIA was coming on strong. They had released their GeForce256 chip, which took a nice performance lead over Voodoo3. As a follow up, NVIDIA brought the GeForce2 to market. These two parts offered a considerable number of additional features that 3dfx did not provide with Voodoo5. While 3dfx did offer anti-aliasing that was considerably superior to NVIDIA's, they had a tough time selling it due to NVIDIA's aggressive marketing and technology demos. From this, 3dfx lost the majority of their developer support and a considerable amount of consumer confidence.