I have a xps m1710 with windows vista and yesterday I got a pop up message at the lower right hand side of the screen telling me to update my sound drivers.  I updated SigmaTel but consequently I lost all sounds.  I rolled back the drivers and still nothing.  So I deleted all the sound drivers and went to dell.com to get the drivers.  But after installing them, I still have no sound.  I'm currently trying to either find a way to fix the new drivers or install the older ones.  Thanks for your help.