Building it on your own
This is the task of selecting three things: the Desktop PC, the Display and the Speaker System:
The most important question is what you would like for your computer to do besides being a Home Theater system, because the Home Theater part is easy – you need to select a computer with a heavy-duty video card (like an NVIDIA GeForce HDMI card, GeForce 9500GT for example), a Blu-ray drive, and a TV-Tuner card so that you can watch TV on the computer as well. If you are looking for not much besides document processing, and limited media manipulation, a dual-core or a triple-core CPU will suffice. More heavy duty applications, with heavy media manipulation would require at least a quad-core. Regardless of what processor you choose, you’ll want lots of HD space. As stated above, there is the option of custom-building the Desktop PC.
We mentioned Blu-ray already, and really it doesn’t make any sense to have anything non HD nowadays. Screen size and resolution are considerations here. Depending on how you use it, you may also think of a wall-mount (an HDTV) instead of a desk-top display. With a wireless keyboard and mouse, you can probably use the computing capabilities from anywhere in a room. A word of caution: having a big display can result in reduced privacy, so you may want to keep a small display hooked up that you use for personal computing.
Here you want the best possible deal. Make sure you have a top of the line sound card that supports at least Dolby 5.1 and get speakers to match that. Any number of options are available. Consider getting speakers professionally installed for the best movie experience.