I have a Macbook Air and downloaded Logic Pro 9. How do I safely move Additional Content to external drive & use the external drive to run Logic when creating?
Simply copy the additional content (basically the Apple Loops) over to an external hard drive and when you next open Logic open a Finder window at the new location of the Content.
Drag the folder containing all the moved Apple loops onto Logic's Loop Browser. Logic will now re-index the Loops.