Don't trust the opinions of self-proclaimed, unqualified experts on copyright law. Educate yourself on what is and isn't legal. Below are some sites that may help illustrate some of the important principles and guidelines related to copyright law.
From the Z. Smith Reynolds Library Copyright Resources A great starting place on this topic.
From Other Universities...
University of Texas' Online Crash Course in Copyright
University of Chicago Statement on Peer to Peer Sharing
UNC Policy on Copyright Infringement
Copyright Central at MIT
Peer to Peer at the University of Virginia
Cornell University: Statement on Illegal Use of Filesharing
From the Entertainment Industry...
Music United
From the Source...
U.S. Copyright Office
The Digital Millennium Copyright Act