I have narrowed things down a little more. I can get my system up and running (relatively) stable by disabling 4X AGP in my bios.
This SUCKS. Why am I spending money on this card if I cannot run it in at LEAST 4X??? My old geforce2pro ran at 4X. Why not my brand-spankin new geforcefx 5600 ultra?!
Well, I am going to poke around some more and see if I can get things moving, perhaps with a different driver.
Is there some way to get the nvidia drivers to force 4X AGP even if its disabled in my bios?
Does anyone think I may be better off using the NvAGP instead of agpgart?
Thanks again to everyone for being so helpful (this would be TONS more frustrating if I was dealing with this on my own!)
Je ne sais RIEN!