According to a website that eludes my right now, while it is technically possible to buy a video card that will pass High Def vid and a bitstream audio (TrueHD or DTS-MA) over HDMI, the sad truth is that the HDCP protections get in the way of making this a viable option without some code cracking.
And that is the heart of the matter. HDCP requires both a protected video and audio path. They must be separate. That makes the hardware doubly complicated and adds expense. I don't think that the hardware vendors are going to try too hard to deliver low cost hardware given the luke warm reception the htpc has had thus far.
I honestly think that Sony would be most happy if the whole HTPC thing died an ugly death.
The theoretical advantage to the HTPC was entertainment 'vitrualization'. The ability to use one piece of hardware for multiple entertainment functions. The reality seems to be far from that.
