Dave Weinberger gives a good synopsis of what the purveyors of DRM are trying to do:

"Pardon me while I state what's been dead obvious for years now: Microsoft wants to be—is—in the entertainment business. Microsoft thinks it will win if it can be the preferred player of Hollywood content. So, to persuade Hollywood (and other Big Content providers) to offer their goods in Microsoft proprietary formats, thus locking the audience into the MS platform, Microsoft has spent billions of dollars devising the uncrackable platform. If that means turning your PC into a player rather than a computer, so be it. Vista is all about protecting Hollywood from its audience, even if that means degrading the utility and performance of the PC that runs Vista."