How Do I Position My Loudspeakers and Subwoofer For My Home Theater System?

About.com has a nice Q&A for some speaker setup. So check it out if you're interested in or wanting to improve your current sound setup.

To aid in your speaker setup, take advantage of the built-in Test Tone
Generator that is available in many Home Theater Receivers to set your
sound levels. All Speakers should be able to output at the same volume
level. A inexpensive Sound Meter can also help with this task.

Read the rest here.