MuVChat uses a Microsoft technology called DirectShow that relies on certain  components to be installed on the computer.  Some Windows machines do not have all of the components necessary for DirectShow to run successfully.  One of these missing components is a program called AC3Filter.

If you are trying to run MuVChat on a Vista or Windows7 system and have no sound, go to this website to download the most current AC3Filter - http://ac3filter.net/projects/ac3filter/releases

• If you are running a 32bit version, install the Lite version of the AC3 Filter
• If you are running a 64bit version, install the Full version of the AC3 Filter
  

No further configuration is necessary.  If you install the Lite version, you should be good to go after it is installed.  If you pick the Full version of AC3Filter, you have also installed a program that provides lots of other configuration options for your audio.  Feel free to play with this program as you’d like, although it is not needed for MuVChat.

After installing the AC3Filter you should now be able to run MuVChat as needed.

The 'no sound' problem may be applicable to other versions of Windows, but it is a known problem with Vista and Windows 7.