Hi, I'm about to put my 13" MBP (last late summer model) into an Apple provided box to get the trackpad repaired for that issue where the cursor starts going crazy for no apparent reason. They told me to do a complete backup first, just for safety. I'm running Lion, and I have a WD USB external drive to back it up to...but I just realized I have no idea how or what to back up. A colleague suggested burning an image of the whole disc and tranferring it to the external drive. How would I do that? Thanks!