Thanks to Owen for letting me know that there are new 4 in 1 Via drivers up. The link they have on that page is broken, so use this one. I'm not sure what 4.20 does, but I'll be sure to test.
[...] Well I've done some testing with the new Via 4 in 1 drivers, specifically gaming testing with Quake Arena, and here are the results. Everything seems to be the same. I saw no performance increase or decrease with the new drivers, and all of the AGP features are still enabled with the KX133 with no tweaks. I used an Athlon 500 with 256MB of NEC VCM SDRAM, and a Diamond TNT 2 Ultra for the testing.
Je kunt ze drivers hier wegtrekken.