intel 945gc use onboard video WITH pci-express?

I wasnt able to find any information pertaining to my board itself, but i have a intel 945gc mb and im running an ATi X1050 pcix16 which supports dual monitors (also vista home 32bit) great! however i know it sounds silly, but i actually need all 3 of my monitors to be working, is there any way to re-enable the onboard? it just dissapears when the pcie is in and reappears when its gone, if not, will installing a simple pci video card allow me to add the third monitor? thanks.