Hi,
I have a Sony VAIO VGN-AR41S and I had the problem described in this article (code 10 error for a SigmaTel HDAUDIO driver in Windows 2003 SP1). I have tried installing the drivers from DriverPack Sound B. All of them had the same problem, but one of them miraculously worked: the 26th of May 2006 driver, version 5.10.5067.0, and the BIOS update is not required, neither is the change in any *.INF file was required! So go ahead, get the DriverPack on the home page and get the sound working! 
My HWID is:
HDAUDIO\FUNC_01&VEN_8384&DEV_7664&SUBSYS_104D2200&REV_1002\4&159680D3&9&0001