Another great tool in the kit for control of the operating system.
Nircmd is a command line app witten by NirSoft (it is free!), you can get it from here:
http://www.nirsoft.net/utils/nircmd.html (download is at the bottom)
This page also has a quick summary of some of the thinks Nircmd can do. This is the full help page:
http://www.nirsoft.net/utils/nircmd2.html#usingNircmd commands are executed with the "Run Application" action in VA. I pu the executable in the VA_APPS folder so it is easy to find. Then it is just a case of adding the options you would supply to Nircmd on the command line to the "With these parameters" box for VA. For example:
Run Application: {VA_APPS}\nircmd.exe
With these parameters: muteappvolume focused 2
Will mute the current active application, not the whole system.