So, just got the HDMI cable for our nice big TV, and decided to test it with the Avatar DVD. It looks so much more fake now. Before, it looked almost passable as real, now it looks like a cutscene from a video game. Anyone else have HD Weirdness?
Ummm.... Did you mean to say DVD or Blu-Ray (or HD-DVD, if you're a dead-format affectionado)?
If you are watching a DVD on an HDTV, then I'd say your player's upscaling algorithm isn't all that great, and the transmission quality on your old cables masked that fact. Switch over to an HD channel or play a Blu-Ray, and it should look much better, because you'll be playing HD content at its native resolution, instead of stretching a 480p image across a 1080p monitor.
Now, if you are watching the Blu-Ray, it might be that the movie dived deeper into the uncanny valley for you. The finer details, being more apparent, made it more obvious that you were looking at a whole lot of artificial effects. You might try testing the setup with a movie that doesn't rely so much on computer-generated effects to see if you get the same effect with practical effects and live actors.