Forgive my ignorance here. I'm giving my old 13" Macbook to a family member and want to delete all of my info for security. I can't find the original Install DVD but do have the original Snow Leopard disk I bought as an upgrade. If I wipe the machine with Disk Utility and then reinstall Snow Leopard, will that do the same thing as using the original Install DVD with an upgraded OS X? Thanks in advance ...