Okay, when you say you "migrated" to Windows 7 Ultimate, did you do a new clean install or an upgrade from another version of Windows 7?
You may have to reinstall the drivers, do you have the driver disc for your motherboard?
Windows 7 is NOT supported by the ASUS website for you motherboard model. It uses the ADI AD1986A audio chipset.
The ADI website does not even list the drivers anymore for you audio chipset. Have you tried Windows 7 Update?