How to disable Onboard Graphics?

How to disable Onboard Graphics from BIOS and windows xp sp2.
Mother Board is 945GNT.

It gets disabled by itself if you install an AGP card.

im not sure it works like that in every motherboard , look for graphic media accelerator/integrated graphics/gma/onboard video , in some motherboards it can only be set to use less ram and cant be disabled

I’ve never seen this behaviour on Intel’s chipset, I do know that some ATi/nVIdia chipsets work that way though.