Windows 7 Speaker Setup
Open up the Windows 7 Control Panel, then go to the Sound application. Under the Playback tab, you will see a list of items supported by your system. Usually, the one labeled Speakers is already checked. Click on Speakers, then click the Configure button in the lower left corner of the window. This will bring up the Speaker Setup window.
The Speaker Setup screen is where you tell Windows 7 what type of audio output you are using. In the example graphic here, you see that my system supports four options: Stereo, Quadrophonic, 5.1 Surround, and 7.1 Surround. Choose the option that matches your own speakers, then click the Test button and it'll play a sound through each speaker in order to identify their position.
If the sound does not play through the appropriate speaker, double-check your connections to make sure everything is plugged in correctly. It's easy to mix up all those surround sound wires when you have so many different speakers.
(Image Screenshot from Author's PC)