Lost Sigmatel audio

Hi
last day I run Windowsupdate and downloaded "Intel Corporation driver update
for Mobile Intel(R) 965 Express Chipset Family" on my vista ultimate.
Since I rebooted the audio is no longer working.
I had no system restore enabled so cannot roll back. I tryed to reinstall
original Dell drivers with no luck.
The Peripheral seems perfectly working, but any program trying to output
sounds simply seems muted. Only WMP11 tells me "Windows media player
encountered a problem while playing the file. For additional help click web
help" that brings me to

http://www.microsoft.com/windows/win...nalid=887C003A
but this page has general unuseful info.
Now I'm stuck with no audio.
Any idea other that format/reinstall (Dell assistance solution!)?
Thanks

Didn't mention I'm using x64 Vista.