Could you tell us the model of the video card and brand? Does the Windows
desktop load for you to at least access the Internet and download the latest
software and device driver for your video card? If thats not possible, I
would suggest doing a system repair:
Boot from your Windows Vista installation DVD:
Choose your language settings, and then click Next.
Click Repair your computer.
Select the operating system you want to repair, and then click Next.
On the System Recovery Options menu, click a tool to open it.