By default Windows 7 will now automatically reduce the volume of your PC's sounds whenever it detects you're making or receiving PC-based phone calls. If this proves annoying (or maybe you'd like it to turn off other sounds altogether) then you can easily change the settings accordingly. Just right-click the speaker icon in your taskbar, select Sounds > Communications, and tell Windows what you'd like it to do.
Subject: Tweak PC volume 
Sun Apr 04, 2010 12:21 pm