The question then becomes how and to what extent intellectual property should have protection. I am not sure whether you are arguing for a free right of copying and trading any intellectual property, from patents, to copyrights, to trademarks and tradenames, to whatever.
Perhaps you are contending only that because technology now makes mass copying and transfer of copyrighted music feasible, copyright protection should be withdrawn or limited. Although the law must recognize the facts of (modern) life to maintain its force and effectiveness, I contend that what Napster is doing is really nothing but a transparent subterfuge for wholesale copyright infringement.
To take your gun analogy and run with it, Napster is not the innocent bystander being blamed for the perpetrator’s misuse of a gun. Napster is engaged in the equivalent of organizing a safari to your private game preserve, handing weapons to all the participants, pointing out the game, and then pretending not to be responsible when the participants poach the game.
The idea that everyone is just a "friend" who showed up at a commercial website to share tunes, sounds way too much like the Clinton’s defense of their use of the Lincoln bedroom: anyone who pays me a hundred thousand dollars is my friend. Anyone who lets me copy music for free is a friend.
Although I acknowledge the difficulties in policing copyright law in the current environment, I must respectfully disagree.