As far as games, I've been having the most fun with Rainbow Six Vegas. Its just plain fun. Head shots really make a big difference too, so if you have any ability to get a headshot in, you'll get a lot of kills. I'm not usually great at these games, but its one of the few games where I've had great moments!
For movies, I've downloaded an episode of Jackass (SD) just cause I wanted to check something out and I like Jackass
I also downloaded an episode of Star Trek in HD. I like Star trek and wanted to see how it looked in HD. It looked really good, but its not widescreen. I imagine its got 720 lines still, but not 1280 rows.
I haven't tried the movies yet - The ones that interested me will be available on HD-DVD, so I am waiting for that.
See on Xbox Live - My gamertag is Maytrix.