Thought I'd share a little trick on how to obtain free (or very cheap) 3dfx pci video cards. Its worked for me twice now.
Check out the free stuff section of craigslist and look for "curb alerts" or people giving away old PCs. In the NY area there's 50 or so of these postings every day. Anyway, just send an email to the poster and ask them if its still available and what kind of graphics card is installed. Most people won't even respond. Some respond but don't have a clue what you're talking about.. Some respond but have the wrong type of card, etc... But after about 20 or so attempts, a guy came back and said he had a pentium pro 200 and the graphics card was a 3dfx voodoo 4! It was obviously PCI because the pentium pro predates agp. Anyway, the price was right: free. Just took 30 min. of my time to send off the emails..