Try doing what I said above, select bog standard vga card, delete all the drivers associated with the Vanta, stick your new card in then load the drivers that came with the disk, in you don't have a disk with the card download drivers for your card from the manufacturors site, once you have it up and running you can always look for better/faster drivers later.
They are a pain in the arse to install are graphics cards, there is half a dozen different way of doing it, had half a dozen different ones in my kit, I think the only ones that are a doddle are the Matrox cards, stick it in shove in the driver cd and its all done for you.
Good luck.
