okay go into add/remove programs in control panel & uninstall your onboard video drivers, then right after putting your new video card in your computer as soon as u turn on comp. tap the "delete" key this will bring u into your bios , now find your onboard video and disable, your doing this cause you can't run yoyr comp. on an onboard video chip and your new video card at the same time, right? so disable that mofo and forget about it too lol....now once back in windows again install new video drivers for your new card
go to ati.com or nvidia.com whichever kind of card u gots.