I stummbled on this article from Peter Gutmann explaining the copy protection built into Windows Vista. The article states that Vista will down grade video and audio reproduction on protected media if Vista can not protect the media.
Vista also has built in tilt bits to help protect from hacked hardware. Vista checks its hardware regularly against these tilt bits to see if it is still valid. It sounds like Microsoft is a little paranoid about getting sued or being hacked. I am not sure any of this extra code will make Vista more secure from hackers and malware. In fact it might make it easier for hackers to mess with your system. Vista’s tilt bits might have opened a door for hackers to change a hardware configuration on your system which would cause Vista to do a “Reboot” in order to restore correct functionality.
Check out Peter Gutmann’s full article here.