And yes, it appears that DRM is to blame. Paul Thurott is a columinst who makes his living writing about Windows products, so he certainly is inclined to be biased in favor of Microsoft products. He decided to hook his HD-DVD drive from his Xbox360 up to his Vista PC. Vista easily recognized the drive and downloaded the necessary drivers for it with no problems.
The problems showed up when Thurott installed software so that he could watch HD-DVDs. It didn’t like the drivers for his video card and his monitor. Installing the drivers turned out to be a nightmare, with numerous bluescreens, and it was only a matter of luck that he was able to get his system up and running again. You can hear his adventures with it here. He has a couple of cutting points about Vista, and he did eventually manage to get things working. (But not in a way that would probably make Microsoft very happy.)