Hi,

First things first, not every flat panel TV needs to be wall mounted, most people put them way too high and they all come with a base that you must remove first.

If you have a desired location and know where you want your equipment then what you want to do is create a passage-way from the TV down to the equipment through the wall. Use the low-voltage old-work boxes and dress them up with hooded face plates. Then you can run whatever cables you may need/desire for the equipment you add.

Std. DVD, with upconversion or BluRay can carry everything via HDMI. You want all cables to be "in wall rated" which is for fire safety purposes most of all.

If you have other equipment that requires either RF, composite, S-Video, Component, RGB, or HDMI you have the feed-through in the wall cavity already in place.

The AC power however is separate and must have an outlet behind the TV fed via proper electrical installation techniques. Keep the Romex and signal cables as far apart as possible and avoid parallel runs beyond 2-3 feet.