I'll have to give you and anyone else that ends up seeing the identical problem the same recommendation I added on the SP1 thread for trying to remove the new set that seems to have been put on during the update and browsing the software disk for the originals following a restart once you see the new hardware found message or yellow marked items in the device manager following the uninstall there.
For those with cards installed and not using onboard the defaults for the audio console or volume control panel seem to take over once the service has finished installation. As most will remember SP2 for XP also saw some initial problems when that first came out. People were hesitant to see it go on for some time after. Hey good news on that part at least! But someone will hear about the little bugs just the same.