If you've not already done so, you might want to check out these fixes. I can't guarantee they'll do the trick, but I know they've worked for quite a few folks.
That being said, MTW does have a notorious time running on newer Nvidia cards from the 8xxx and 9xxx series. (Of course, Nvida & CA point the finger at each other, claiming that it's the other company's responsibility to fix the problem.) Some people are able to figure out a way around this issue, some aren't.
In any case, I wish you luck! I'd be very sad if I couldn't run MTW anymore, so I strongly sympathize with your situation.
EDIT: Gah. Forgot to add the link.
< Message edited by martok -- 3/7/2010 5:31:14 AM >
"Evil is easy, and has infinite forms." -- Pascal