If you are experiencing garbled with the sound in Windows 7 on motherboards with the built-in SoundMax chip, try downloading the drivers here:
First un-install the existing SoundMax drivers (that were probably downloaded from Windows Update). Make sure you chose the option to delete the software. Now temporarily unplug your network connection (so that Windows does not download the drivers again) and re-scan for hardware changes. Then update the driver for your sound card by pointing to files in the link above. The sound should start working immediately. You can re-connect your computer to the Internet now.
I’ve been told by a member of the Product Team that this should not be necessary in Beta 1 of Windows 7. The in-box or Windows Update drivers should work just fine. I plan to verify that shortly as I upgrade my box to Beta 1. The pre-beta version that I have is running so smoothly I just haven’t felt the urge to upgrade! Please leave a comment here if you are still experiencing the issue with Beta 1.