Well, follow Kareemy's advice, and you should be ready to roll.
The reason this worked is that setting nvAGP to "1" tells the driver to only try nVidia's own AGP implementation. For unsupported motherboards, like yours, this will fail, and the driver won't use AGP. That's why we suggested you try AGPGART.
Offhand, I don't know if AGPGART supports your chipset or not. If you had trouble loading it before, it is likely that there is no explicit support for your chipset. However, your chipset is pretty similar to some other Via chipsets, so when you specified the "try unsupported option", it probably loaded up some generic Via support and worked.
From that point, all you needed to do was change your nvAGP option so that it would try to use AGPGART. Changing from "1" (try nVidia's AGP implementation only) to "3" (try AGPGART first, and then try nVidia's AGP implementation if AGPGART fails) accomplished this. If you want to confirm this verdict, you could change nvAGP to "2" (only try AGPGART). I would expect things to keep working fine.
If you're feeling a little adventurous, you can explore trying to get nVidia's AGP implementation working with your chipset. The driver includes just enough source to try this. If you're interested, I'll post some advice. If it were to work, it'd probably be a good idea to forward the results to nVidia so that they can explore supporting your motherboard better
In any case, I'm glad to hear you're up and kicking!