Nick, the person you should send a PM to is Saturn.
He's built and used a HTPC for some time and is quite knowledgable about the innards and software, advantages and disadvantages in a practical use situation. Many of us here have excellent computer skills but i don't recall anyone else actually built and uses a HTPC specifically.

You should try a search on this subject. It has come up before and the thread did get lengthy.

"Those who preach the myths of audio are ignorant of truth."