DRM restricts the kind of media content you can use on your Vista machine. This is meant to make life harder for pirates but in practice, as Sony learnt, it can make life harder for honest users too.
Alex Ionescu said on his blog that he had written code which could be used to bypass Vista's DRM. Ionescu has not published the code but promises in a later post to publish "some safe, generic, proof of concept code that targets what I believe is a flaw in the Code Integrity/Driver Signing model.". Read more at TheRegister