just switched the old: thinkpad with xp the new: powerbook with osX i notice that when i rip a new cd in iTunes 4.5, it is in that apple format (mp4) ?? however, all my iTunes songs on the xp system are mp3 questions: 1) can i copy those old xp files to the mac and have it work with iTunes on powerbook and iPod ? 2) is there any quality difference between mp3 and apple ? 3) what is the best way to transfer a multi-GB collection ? thanks !