Moving iTunes music library

Do you have an iPod? If you do, simply go to the iPod tab in iTunes, enable disk use, and then copy your entire library to the iPod via the desktop icon. Plug the iPod into the new computer and drag the music into your new library.

Or, if you don't have an iPod, and you've got a firewire cable lying around, just mount the MacBook as an external drive for the eMac using FireWire Target Disk Mode. Just plug the two together, start up your MacBook (or eMac, whichever one) holding down the "T" button at startup. It will mount as an external drive on the other computer, and now you can drag and drop from one drive to the other.