Disabling onboard graphic chip

This is for my brother-in-law. I only realised that not all BIOS can have access to the disabling function. Some gotta do it via Windows Device Manager itself. But this seems to be for Win95-98. Not sure if this is workable for WinXP...

http://forums.techguy.org/windows-95-98-me/528300-turn-off-onboard-graphics.html

After snooping around the Net, another workable solution would be to boot using the onboard chip, DISABLE the video adapter under DEVICE MANAGER, choose NO when asked to reboot, SHUTDOWN the system, plug-in new card and Windows should detect the new card and ask you to install the drivers for it.