I'm afraid I'm not gonna be much help, but I can tell you it should definately run on that card.
Ive got a Creative Annihilator GeForce2 Ultra / DX8.0 / 6.31 det And it runs fine.
I can run with 6.50 too, but I loose my OC tab & Ive been to lazy to lookup how to re-enable
it for the 6.50s since I saw no difference between the 2 drivers.
Maybe try reinstalling DirectX 8, if it asks to reboot when its done, then it
may cure your problem, however if Directx 8 install just says its done & displays an "OK"
box without the reboot option then DX8 was ok.
Are your video settings for your card "tweaked"?, Like having some default options
turned off that would normally be on, or visa versa?
Youve gotta get that game running, its awesome!
If you do get it running, try the "on bike rider view", now thats one
heck of a joyride.
If you need to compare system settings for reference, just email me, I'd be glad to help if I can.