Hi there,
I have the exact same machine (Gateway M-6850FX) that I also downgraded to XP Pro. Since then I can not get the audio to work at all. In the audio devices it will only give one option and that is "ATI HD Audio rear output" which is sending everything to the HDMI port. There is no choice for onboard speakers. The bios settings the laptop show and allow changes to are very limited and none have to do with sound.
Does the solution you got for using multiple monitors have anything to do with the other video board funtions for sound?
Not having any audio is driving me nuts.
Thanks,
Mike