I'll take a stab, though you're a bit of a miser with details.
"udev is a daemon which dynamically creates and removes device nodes from /dev/, handles hotplug events and loads drivers at boot time."
Therefore, your video card should be detected at boot time with the proper module being loaded automagically. Seems like you have a BIOS issue (may be an option to favour AGP.) However, you can try blacklisting the onboard module.