The reason I've never really considered an HTPC is all the problems I have with a regular PC. Do I have to constantly be thinking about viruses, spyware, deleting temporary internet files, cleaning up the system, defragging, backing up files, etc.?
Also, what kind of bootup time is there? With my existing HT, everything turns on or off with one button (good ol' Harmony!), and there's a bootup time of a few seconds. But is an HTPC similar to a regular PC where I have to wait a minute or so? If I want to watch a movie or TV or listen to music, I don't want to have to wait -- even if it's only a minute. I want to pop it in and watch it NOW.
Those are my major reservations. For the moment, anyway.
cheers,
supervij