Removing on board video card

I have installed a 3dfx Voodoo 3000 video card on my Compaq Presario system. The problem is that I cannot seem to diable my onbaord video card no matter how I try. I have changed it’s settings in the bios to as low as you can set it, and I have diabled it in Windows.However I continuosly have to re-install the Voodoo cards drivers and reset my display settings (this happens at least twice a week) any suggestions?