backing up/deleting files from itunes


I can't figure out an easy way to do what I'd like to do. I'd like to remove all mp3s from the library that aren't located in a playlist already, as I have way too much stuff. Another option would be to back up the playlists and delete the whole library, then recopy the playlists to itunes. However, I can't find a way to simply drag mp3s from a playlist into a desktop folder; seems I'd have to find them all in the library first and drag them individually, which would take forever. Is there a way to trash every mp3 that isn't in a playlist? Or an easier way to back up just those songs I currently have in playlists, then delete all other files? I have about 25g in the library, and want to get it down to about 6g. Thanks.