Most of the people I know using HTPC's run thier media off an external HD anyways so the argument about the mini have a small HD is kind of pointless. I also think with the new mini being N capable you can now effectively stream your media to the machine over you network with your server and other goodies in another room. I havent seen too many small footprint PC's out there and the really cheap guys are full sized towers. My idea of a HTPC is something that goes on the shelf with the rest of my equipment. Also the point of a HTPC is HOME THEATER. So a big picture is nice but if your running all of you audio off you TV speakers your a tool anyways. So the optical out running to my receiver is a given no matter what I have hooked up.
TV.