Try this,
First take out any video cards you have in it and boot up with the integrated one. (make sure you enable the integrated one before you do this!!!)
Start windows up.
Start, Settings, Control Panel, System.
When it pops up click on the Hardware tab.
There should be a button somewhere in there that says "Device Manager" Click it.
A window will pop up with device categlories, you need to click on the [+] to the left of "Display Adapters". If there is a video card listed in there other than your integrated one, right click on it and click uninstall.
Once thats done restart and disable the integrated card.
Shut it off, install your new card.
Turn it on and when windows is done loading you should get a popup saying something about new hardware. If you click that it should take you too a wizard that will search for drivers for the card.
If it cant find the drivers you will have to download and install them manually.
Just write down the card name, model, whatever else is on the card to identify it.
Then go to the manufactures website and you should be able to get the drivers there.
Hope that helps, let us know how it turns out.