I bought a WD 500 GB external hard drive. I plugged it into my MBP to be able to back up files because I am planning to sell it soon and upgrade to a MBA. I did this via time machine. Nothing manual, it does it automatically. There are several times it does this and neatly stores each "back up session" in a folder labeled with the date and time. 3 questions (keep in mind i am running 10.5.8, i know i just never got to upgrading the OSX): 1. If I wipe my MBP after a back up is complete, sell it off, and buy a MBA, will all my photos, music, etc be saved? 2. Lets say I purchase a new MBA, plug the external HD into it, can I manually pick what I want to transfer to the MBA, then set it up as a time machine backup for the new MBA? 3. Can I delete previous back up dates since there are more recent back up dates being put on?