How to set up a 5.1 home theater system?
Home theatre systems normally come in three digital audio applications; Dolby Digital 2.0, 5.1 and 7.1, with the decimal number (.1) being the subwoofer, and the real number being the number of speakers that the receiver supports. So, a Dolby Digital 5.1 home theatre system would have a subwoofer, two front and two rear surround sound speakers, and a centre channel speaker (5 speakers and a subwoofer).

The centre channel speaker is responsible for the vocals, or the actor's voices, and is the most important speaker with regards to quality and placement position in the room. The main factors in figuring out how to set up a Dolby Digital 5.1 home theatre system would start with the placement of the television set, which should be positioned so that no windows or entrance doors are in the reflection of the screen. Too much backlighting will ruin the picture, and make the darker scenes very hard to make out.
Before hooking up the individual speakers, connect all of the wires to their respective connections on the rear of the receiver. Run the wires to about where each speaker will be placed, and add about two to three feet of extra wire, in case of minor adjustments later. The front channel speaker should be positioned as close as possible to the television, so that the actor's voices appear to come from the screen. The subwoofer placement should be not in a corner or under any furniture, but other than that the placement can be anywhere in the room so that the subwoofer faces the listener. The front surround sound speakers should be placed at least three feet from both the receiver and centre channel speaker. If your room is larger, make the separations greater, as long as you can match the distance between the front speakers and the receiver with the distance between the front speakers and the rear speakers. Place the rear surround sound speakers equidistantly from the front speakers and the centre channel speaker.
The most important thing to consider when placing the surround speakers is to make them all focus on the sweet spot of the listener. The sweet spot is defined as the position in which the viewer most frequently sits to watch the television. With the speakers positioned equidistantly from each other and the sweet spot, make sure that they are all positioned to face the sweet spot. Once all speakers are positioned properly, use the owners manual of the home theatre receiver to calibrate the speakers, to make sure that you get the same amount of volume from each speaker. Once this has all been done, it is time to watch a movie!