Here is a simple parts list for an HD capable Home Theater PC. Thanks to the inclusion of on board graphics that handle the work of HD content playback, the days of needing a separate video card and a powerful processor are over. Please note, this guide is for an HTPC that will not be used for gaming.

Motherboard: Asus M3N78-EM. The built in nVidia GeForce 8300 video chipset will handle HD content up to 1080p. This takes the load off the CPU and has the GPU do the heavy lifting. The built in audio also supports 8 channel LCPM sound for Blu-Ray playback. Link

Processor: AMD Athlon X2 4850e 2.5GHz. With the GeForce 8200 graphics chip on the motherboard you don't a powerful processor to playback HD content. This processor, runs cool at only 45 watts, and is inexpensive to boot. Link

Heatsink/Fan: Scythe Ninja Mini SCMNJ-1000. This heatsink/fan unit fits perfectly in the case specified below. Also, since the CPU generates so little heat, you can even remove the fan and run it passively with no problems. Link

Memory: G.Skill 2GB memory kit. With the cost of RAM, 2GB of ram should be considered the minimum for any new HTPC build. Link

DVD Drive: Simply here to round out the parts list. You'll also need this to install your operating system of choice. You can, of course, subsitute this with a Blu-Ray drive of your choosing. Link

Hard Drive: Western Digital 640GB. These drives are fast, cool, and quite. Feel free to change this to any drive of your choosing. But remember, if you plan on adding tuners to record HDTV, you'll need enough space to hold all the tv shows you want to record. Link

Case: Antec NSK2480. This case is small, runs cool and quiet, is reasonably priced, and includes a good quality power supply. A good all around HTPC case. Link

So there you have it. A simple parts list to build an HTPC for under $450. You can then add an operating system of your choosing like Windows Vista, or Linux. Also, you can add whatever tuner cards you wish if you want to record your favorite TV shows.