My htpc is connected with hdmi to my pio 1021 amp ----> panny vt25. The htpc is on 24/7.
I have my harmony setup this way
switch amp to htpc
live tv button
When this works which is the majority of the time its just like a cable box... family approved!
However sometimes when starting up, WMC would be in 4:3 mode (black bars on the sides) and the only fix would be to close wmc and open it again.