If you are using a pretty recent distro for example MDK 9.1, you should be able to get the AGP to work without any magic drivers, other than loading up the NV specific drivers from Nvidia. I have a VIA board and all worked pretty much out of the box.
But, if you want to read a little bit more, see
http://www.viaarena.com/?PageID=2 for specific 'distro' stuff.