Installing a new video card is usual not hard but I have had a few that were difficult.
As long as you follow a few general guidelines you should be just fine
First check to see if your motherboard supports the new video card with the BIOS version you currently have, sometimes you will need to flash your BIOS with a newer version that supports your new video card.
Just before you install the new video card, boot up your machine and uninstall the drivers for your onboard video, then uninstall your display adapter (onboard video) from the device manager. Then shut down your machine and install the new video card.
The reasoning behind this is that without any other video drivers installed windows will use the default drivers for the new video card that it finds on boot up thus enabling you to still see the screen.
If for some reason you do end up with a blank screen all you have to do is restart your machine in safe mode, safe mode also uses windows default video drivers.
Once in safe mode you can then install the new video drivers.
