Hello all, Currently I own a Black Core Duo Macbook that I bought used off of Craigslist about two years ago. I'm planning to sell it and buy a base 11" macbook air. I have two questions that I haven't been able to find answers to: 1) The person who sold me the macbook had lost the installation CDs. In order to get it in salable condition, I want to wipe the hard drive and install a fresh version of OS X Leopard. Is there a way to do this without the installations CDs and without having to buy Snow Leopard? I will have at my disposal: the black macbook w/ CD burner, the MBA, a 2GB flash drive, and a 500 GB external hard drive. 2) Since the macbook air only has a 64 GB hard drive, I'm planning to keep most of my media on the external 500GB hard drive. I've never used the external drive for anything aside from backing up time machine (in a 200GB partition), and I want to know how an external drive functions on a day to day basis. I'll be keeping pictures, music and movies on the external drive. What happens when I unplug the drive? Can I keep a small selection of songs/movies/pictures on the air for when I'm away from my desk? Thanks!