Well, Voodoo4 PCI should be ok for a while, I have voodoo3 3k and still pretty happy with it. I think the best PCI board you can have now is Voodoo5. Since 3DFX just went out of business, you may still be able to get it now but there isn't gonna be any driver update or tech support anymore. That's pretty sad too because 3dfx (voodoo) always have PCI support for almost all their cards. Other than that, GeForce2 MX base video cards also support PCI, but nvidia (company manufacture GF base chips) doesn't have PCI support for their higher end video card, so who knows how their PCI support gonna be in the future.
Actually it is not that hard to install a mobo with APG port. (same procedure with or without APG port) If you got a friend who build a PC before, you can ask him/her to work with you for the first time just to make sure everything is ok. If you done it once, it's not that bad. But it will probably requires you to reinstall windows and all your programs just to avoid any problem, some people don't do that, but I always reinstall everything when I change mobo. So you have to backup all your documents, mp3....so on before you do it. After that, just put in the mobo, connects everything, boot is up and reinstall....that's it!!
If you are afriad of change mobo yourself, you can always make sure you get a AGP system next time you upgrade your PC, but hey if you are really interested in PC, building a PC (changing a mobo is pretty much same as building a PC) is something that get you the most experience!!