These are two of the best sites on the net for finding really great tech deals. Most come with some combinations of rebates and online coupons so there is a little work to do to get the deal, but it is worth it. I love the tag line on dealnews.com - "How to go broke saving money."
SlickDeals.net
Dealnews.com

A good Home Theater PC (HTPC) must start by being a quiet PC. Here are some good tips and links to some components to build a quiet PC.
TechTV - Yoshi's Mods: Project YS-2

I have really gotten into this Xbox scene. The Xbox is a really fun device for not just playing Xbox games, but loads of classic arcade and console games. Here is a link to a list of some of the available emulators for a modded Xbox...
Xport - XBox emulator ports

The interfaces for the Xbox apps most commonly used, Evox and XBMP, are skinnable to your tastes and there are no shortage of skins available here...
AllXboxSkins.com

Here is a link to a good article by Patrick Megenity on the arrival of "software HDTV decoding" coming to a fast PC near you... the second link is to some free HD content available from Microsoft.
The Perfect Vision - High Definition for the PC
Microsoft's High Definition Content Showcase

New project... my company is a Microsoft Partner which means that we have access to all of the software in the MSDN including Windows XP Media Center Edition which is typically only available preloaded on XP MCE hardware from manufacturers like HP. After doing some searching, I have found that I can create a DIY XP MCE computer. I'll let you know how it goes. You can read more about XP MCE at this great forum...
The Green Button Forum - Windows XP Media Center Edition User Community