I think I am going to add either HBO or Showtime (only one, not both)when I upgrade my box to the HD service. Which one has better HD programming? I like HBO originals better, but am thinking about the HD content only.
Which do you prefer?

I can't speak to Showtime, because I don't have it.

HBOHD gets a slight from me. Maybe I'm just not watching the right movies, but they just don't look that great. HDNet Movies tend to be much better. The series are about in the same boat: good but not great. Until the time when they're actually filmed in HD rather than just upconverted (I'm saying that based on observation and don't know if it's fact), I'll just be happy to have the series in a 16:9 aspect.

I have both HBO and Showtime and watch both. That said, I enjoy HBO better - HD quality is the same for both - but HBO has superior programming.

When are MovieVision, ONTV, SelecTV and Z Channel going to have HD channels?

If you are talking HD quality only, HBO routinely shows everything in 1.85:1, even if it is a 2.35:1 movie. Showtime shows it in OAR more often I think. So as far as HD goes, Showtime gets the nod.