I am running tiger on the imac in my signature and am looking to get one of the new alu imacs after macworld. However, I have a buyer for my current machine and it is for a christmas pressie. So i will be mac-less for about a month. I have an external HD to store my info between times - what do i need to do to make sure I have everything transferred.......? Is there anything I need to watch out for, eg what happens to music bought from iTunes? Thanks for your help.