Hi,
When you downgraded to XP you need to reinstall the drivers.
Did you back up the VISTA OS?
This link will help you, but you may have to start over as XP SP3 causes issues when it is installed before the Hardware is working correctly.
http://www.techsupportforum.com/hard...facturers.html
Follow the instructions exactly.
If you run into an issue, POST the issue before going to the next driver.
Hope this helps.
Bill