Everything that you have ever wanted to know about the Motorola DCT-5100 and DCT-6200 HDTV set top boxes...
Motorola High Definition STB FAQ

Here is another list of reference material - this time the focus is audio.
SoundStage! Reference Discs

Here is a list of some reference DVDs to put your theater to the test...
SoundStage! Network Home Theater & Sound -- Reference-Grade DVDs

Hit Dynamism.com to find the latest cool gear and gadgets selling in Japan...
Dynamism.com - Next Generation Japanese Notebooks and Electronics

If you have a small network in your home to connect you HTPCs, Media Servers and Home Office PCs, you might encouter some issues accessing and moving files from one machine to another especially if you recently moved to Windows XP or have a domain server in your home. This is a great guide on some of the more common changes that you can make to your systems to make things run more smoothly.
XP File and Print Sharing Problem Solver from SmallNetBuilder and TomsNetworking.com

Off the home theater topic at bit...
I just picked up this Uniden Expandable Phone Set system at Walmart the other day for $79 at the suggestion of a friend of mine. Really nice! Phone sets have come a long way in the last few years. First off the phons are really small, just a little bigger than my Sony Ericsson cell phone. They sound great and don't interfere with my wireless network and vice versa. The best part is using the features of a multi phone set like intercom (calling from one set to another) and transferring calls (place the call on Hold, and ring the other phone for the other person to pickup), and the speakerphone in the handset. Check it out here....
Uniden DCT646-2

HCCV vs. Firehawk - AVS Forum

Widescreen-o-Rama! All About Aspect Ratios

Some sound proofing products for home theater.
Quiet Solution, Inc.