If you don’t ever plan to play premium content, music or movies that you have purchased from an online store (like iTunes), then you probably don’t have much to worry about. If you do want to play that kind of content however, you should run far away from Vista.
I am mentioning this because of this article by Peter Gutmann. It gets a little bit technical, but the gist is that there are certain pieces of high-end audio and video hardware that Vista will specifically disable playback on because of the “analog hole†idea. This idea is that you can play a DRMed mp3 and “record†the sound in between the PC and the sound hardware. Microsoft’s way around that is to just disable it completely. I have really over-simplified this so I would recommend reading the original article.