HTPC = home theater personal computer... basically just a PC hooked up via HDMI to the AVR with the TV as a "monitor". Keep us posted on your progress.
BTW, after trying the AVR native streaming and WD live (a streaming product), I just went with this:
Echo II - Using Intel Core i3/i5/i7, Value performance
Definitely, there are cheaper options but the wife and I both agreed this was a great investment as we use it every single day for music, NETFLIX, etc.