I also used to be conflicted about this issue until I read the book "Against Intellectual Monopoly" by Boldrin and Levin.  I am now convinced that IP offers very few positives and instead acts as a gigantic weight on the creative energies of society. It stifles research and development, prevents collaboration and competition and leads to consolidation of ownership of ideas in the hands of a few.  Jefferson stated that he was against all forms of tyranny over the mind of man. IP laws aim to control peoples thoughts and ideas. Those who care about the future of freedom would do well to resist them.

I always wondered about IP my self. I personally don't do it, although I did a few years back. I still can't shake the feeling that I am taking someone elses property by downloading a song or movie illegally, even if it is from an evil corporation. This, I think, runs against the foundational libertarian idea of "property-ownership."

However, it can be said that ideas, or media, are not physical property, and thus do not fall into that category. In fact, Agorists believe that stealing music is a form of counter-economics that undermines our political system.

A lot of times, though, it seems like people just really want free stuff and will rationalize it any way they can.