You can also find a related thread in the HTPC forum, specific to the starting HTPC enthusiast. There are a lot of choices to make when building one that are very different from the choices one would make building an uber gaming PC, so check out the advice and share any of your tips.
If you are looking for more advanced tips, there is something for you in the Windows forum. There is a guide to rolling your own Windows install, including all the programs you tend to want to be installed right off the bat. It is also a incredibly long list of handy programs and links to their sites.