I also tested (2.4.21-rc5-ac2) but it doesn't work properly here.
If I use testgart then everything seems to be ok, but when I start X the windows are drawn only in parts. Also the system locks... I have to push reset to reboot.
I also tried 2.5.70 and the nVidia kernel patch, but none of them worked for me. I always get the error thet is explained above.
For some reasons the patch provided by nonolk works perfectly for me...
Asus A7N8X Deluxe
nVidia GeForce 2 Ti (I know... I don't need agpgart...)