You should just be able to boot into safe mode, remove your current card from the device manager, power down, switch cards, power up, install new drivers.
If you want to change to standard VGA drivers, just go to your current card in device manager, right click--properties, driver--update driver, point to C:\Windows\INF, the standard MS video driver should be shown. Click next, next, etc..
Been a while since I've done this, so I might be a little off...not much though!