This PVC (no, not the plastic!) article explains the differences between the different color profiles used in HDTV cameras vs. in HDTV display devices:

http://provideocoalition.com/index.php/cmg_keyframes/story/scene_vs_display_referred_profiles/

This affects especially After Effects CS4 and Photoshop CS4.

After Effects CS3 has a "View > Simulate Output > HDTV (Rec. 709)" option, but this doesn't work properly when compositing video with computer-generated images.

The understanding provided by this article is helpful also for Vegas editors who don't use After Effects.