I'd check out the book, "Free Culture" by Lawrence Lessig. The website for the book is
http://free-culture.org/ but I know it is also on amazon and probably in the library. The book is published by Penguin Press but it is under the Creative Commons license, so if you go to the website you can actually download the entire book in .pdf format, or you can also go to
http://www.legaltorrents.com to get an audio book version if you'd like. Each chapter was recorded by different supporters of the book, so it's not necessarily "professional" audio book quality, but it's good enough to listen to and the information is all intact of course. Finally, at the very least, I'd recommend checking out the flash presentation of "Free Culture" from a speech Lawrence Lessig gave on July 24, 2002, at the O.Reilly Open Source Conference. It's about 30 minutes long and while it talks most specifically about software patents, it relates to the copyright issues of file sharing as well. If you don't want to or don't have the time to check out the book - which I would strongly suggest you do - I would at least check this flash presentation out:
http://lessig.org/freeculture/ And since you, of course, need to explain to people why the hell they should care about what Lawrence Lessig has to say about copyright, etc, here is a link to his bio page:
http://www.lessig.org/bio/short/