also, r u looking to actually move the files or to try and stream them to your PB? be mindful of the computer authorization that iTunes does. while it may not be an issue to simply authorize your tracks on your Mac, u can work around this issue so long as u aren't dealing w/ DRM material. basically since virtually all of my music was ripped on my desktop in MP3 non-DRM format, i just drop the files onto my iBook and then in iTunes go into the preferences>advanced and un check "copy files to itunes music folder when adding to library". this means that iTunes will simply play the tracks from where they r at. this is also a must for streaming audio across a network, bc otherwise itunes will want to copy all the songs i want to play onto my iBook instead of just playing them.