addle, this was a little while back (perhaps 18 months or more) so they may have changed their way of working. Basically my DH got excited at the thought of free MP3s, signed up but was unaware that he was file sharing all the music he had on his computer (most of it from CDs that we had bought and paid for that was simply on his PC for him to listen to) with the world wide web. He thought you could switch the file sharing part of the programme off. One day we received a writ for £10,000 from a bona fide firm of solicitors, he was being sued by the BPI for copyrite infringement, they had screenshots from his PC and everything.
However Limewire and Bit Torrent may have chanted their way of working since then. We would never use them again and currently pay a subscription to Napster and don't get any PC problems with it.