Hello, I am ready to migrate my iMac from Leopard to Snow Leopard. I have a copy of Carbon Copy Cloner and a spare drive with enough capacity to make a bootable clone of my Macintosh HD, prior to starting the upgrade. So, I started CCC and selected the Macintosh HD volume as a source, and selected the external hard drive as a destination. The External drive is formatted as "MAC OS Extended Journaled". As I went to start the clone process a window popped up telling me that I may not be able to boot from the Drive as some format's need to be applied. I tried the process again, and the warning no longer appeared. I cancelled the process as I wanted to be sure this drive will be bootable. Are there any actions I should take prior to starting CCC and letting the copy run? Is there any formatting I need to apply to the external drive?