If you are fast enough you undo those changes with System Restore. And no one accepts DRIVERS from Windows Update. Unless they want to learn why most of us won't do that.

http://www.google.com/imgres?imgurl=http://i164.photobucket.com/albums/u37/joeldsouza/startup-windows-7-sound-disable.jpg&imgrefurl=http://www.bizzntech.com/2009/11/09/how-to-disable-windows-7-startup-sound&h=461&w=414&sz=37&tbnid=-hPZFhchNmADRM:&tbnh=90&tbnw=81&zoom=1&usg=__VtIFJqMgtPTriryMhbJ8WGE7iGU=&docid=f2tCXp8XC-CowM&hl=en&sa=X&ei=9zcAUd_8H4aZiAKtq4DgDQ&ved=0CFEQ9QEwBQ&dur=201 shows the Sound control panel.

I can't be sure if you've been there.
Bob