the card should have at least powered on and gave you a display, did it.
in vista when you installed the card and booted windows should have detected the card and found/installed drivers for it.
no need to install drivers from a disk that came with card.
you might have a bad card (this particular one) try it in another unit..
to try and have this card working on your unit, if possible
then download nVidia clean sweep to remove all current drivers in your unit.
then when rebooting, just let windows install what it calls for.
try that and if it doesn't work then it's a bad card.
(or power supply but that's a reach, right now)
When I install the card, it powers on, but I get no display on my screens. I know the card works, as I've tried it on almost identical desktops in my office. I'll try downloading clean sweep, but does this sound like anything anyone has heard of before?