FiringSquad wrote an article on the problems with both ATI's and NVIDIA's graphics cards with HDCP:
HDCP stands for High-bandwidth Digital Content Protection and is an Intel-initiated program that was developed with Silicon Image. This content protection system is mandatory for high-definition playback of HD-DVD or Blu-Ray discs. If you want to watch movies at 1980x1080, your system will need to support HDCP. If you don’t have HDCP support, you’ll only get a quarter of the resolution. A 75% loss in pixel density is a pretty big deal – Wouldn’t you be angry if your car was advertised as doing 16 mpg, and you only got 4 mpg? Or if you bought a 2 GHz CPU and found out that it only ran at 500 MHz?
As part of the Windows-Vista Ready Monitor article, I was going to publish a list of all of the graphics cards that currently support HDCP. I mean, I remember GPUs dating as far back as the Radeon 8500 that had boasted of HDCP support.