In his blog, Jeff Harell posts some samples of H.264’s quality at various bitrates.

The original MPEG-2 clip was 30.5 MB and had an average bit rate of 7,870.78 megabits per second. An acceptable simulation of the quality of that clip ó not perfect by a long shot, but acceptable ó can be created with H.264 at four megabits per second. I think that’s pretty impressive.

Useful information if you are interested. If you have QuickTime 7 and a reasonably fast connection (as there are video clips for your viewing pleasure), check it out.