I just bought a PNY GeForce3 Ti500 this morning. As I was installing it on my Abit KT7A, I noticed this thread for the first time and was horrified that I might have the same problems. I was kicking myself for not following the board more closely.
But so far so good. I think the fix is VIA's latest
AGP driver released only one week ago. My recipe for success:
Win2k SP2 with all the latest hotfixes
DirectX 8.1
VIA 4in1 drivers
VIA AGP driver 410
Detonator 21.83
No BIOS modifications were done... it's basically at the default "Optimized Settings" for the KT7A.
It's been running a couple hours now with no crashes. Ran Aces High for a bit, did the 3d Mark 2001 thing, played Il-2 a bit. Works great.