Video card changed boot process?

Fellow Geeks,
I added a Matrox G400 GPU to my Intel D815EEA2 mobo (has onboard graphics). I plugged my monitor into the card and made no changes to the BIOS. Now when I reboot I hear about 6 or 7 beeps from the internal speaker and see nothing on the monitor until the XP Pro opening screen.
The experts here advised me that the OS would recognize the hardware change and no BIOS changes were necessary. I suspect that in order to see the BIOS screen (memory test, hit Del to enter setup, etc.) I must tell the BIOS to use the AGP video card and NOT the onboard.
Am I correct?
Can anyone step me through the fix?
Thanks much.

 

most new boards will auto-detect but perhaps that board's behavior takes it a while to switch to the AGP card. I would disable the onboard video and force AGP and see what happens.