In Windows 7, you can go to Sound configuration, select your speakers and click Configure. You will then get a dialog called Speaker Setup. You start with a question about Audio channels (Stereo, Quadraphonic, ...) and in the next step it asks you which of your speakers are full-range speakers.
What exactly are full-range speakers, how do I know if I have them? And what exactly is the difference between checking and not checking that checkbox?