If you are looking into exploring options on Windows Media Center, Beyond TV, Sage TV, and Myth TV- take a look at this article. It is one of the most comprehensive I have seen on the subject and highly recommend a read. The article is a well-thought out, factual presentation of all the features from a consumer perspective (doesn't dive too deep into development).
A couple of quotes that I really like:
“Comparing the HTPC with the VCR is like comparing a truck with a horse and wagon. It can do so much more for you.“
Favorite quote from conclusion:
“When you work in IT and you're pounding away on workstations and servers all day, every day... sometimes the love for computers and what they can do starts to wane. I've fallen prey to this myself over the years. The innovation of the HTPC gave me a jump start, so to speak. It was something that really excited me again and that was why I set out to write this article. I knew when I set out on the journey that it was going to be a long one, but the amount of words I've managed to share with you all has even surprised myself.“
Amen to that!