well, PA Bear, Windows Update has not offered the "right" IDT/Sigmatel High
Definition Audio drivers for Dell machines, so Vista users who use
IDT/Sigmatel audio on Dell computers must obtain updated audio drivers from
the Dell support site instead of Windows Update.
My mother's Dell Inspiron e1405 notebook computer originally came with
Sigmatel 92xx audio drivers 6.10.0.5343 for Vista from the R147073.EXE
package. Since those drivers were not up to Vista SP1 standards, I
downloaded and used the R171788.exe package from the Dell support site a few
months ago to update the Sigmatel high def. audio drivers to v6.10.0.5614.
even though R171788 didn't list the model number of the Dell laptop, the
package did work because the updated drivers found a qualifying "hardware id"
number and still have sound & was able to update to Vista SP1 with no loss of
audio.
You can gather the hardware identification number information of a Sigmatel
high definition audio device by opening the Device Manager window by typing
DEVMGMT.MSC in Vista's Run dialog box, expand the "Sound, video and game
controllers" section to reveal "Sigmatel High Definition Audio Codec",
double-click on that to view its Properties, click on the Details tab, then
change the Property that says "Device Description" to "Hardware IDs".