I was one of the first to get the Windows 7 Beta, but I never had a chance to try it.  Today I really dove in to making it my promary system.  One of the first things I noticed is that I had no Sound out of my MSI mother board.  The driver disk for the sound chip on the main board didn’t work.  I did find the Realtek has released an update to thier HD Audio drivers.  You have to download this from thier very slow site.  Link to Windows 7 Realtek Audio Drivers