Troubleshooting an El Cheapo FX 5200 video card

I'm running a Chaintech made Nvidia FX5200 with 256meg
Both the Vista beta drivers failed to work and I have been incrementally
going back to earlier driver versions starting from the latest ones.
I'm now into the 92.XX series of drivers and I can boot up regularly. It's
very unstable and normally crashes within 1.5 to 2 minutes.
Since I have yet to be able to play with vista and learn it's ins and outs.

Would someone be kind enough to detail out the fastest way to switch Vista
to it's lowest performance settings?
keeping in mind I may only have 1.5 minutes to pull it off.

Thanks!

-Ben