I have on old PC which has my 14 GB itunes library on it. I copied the songs files on to a hard drive and then dragged them into the itunes on my Mac G4. Everything copied except the stuff I purchased from iTunes. (about 70 songs and 4 videos). I thought I could put my purchased stuff on up to 5 computers. Yet the message came up that I wasn't authorized to copy these songs. How do I do this? Thanks for your help.