I have a Macbook Pro running Lion, and I have Lion on a USB drive. I need to securely wipe the Mac and reload the OS. Ive never securely wiped a Mac. 1. Do I use Disk Utility on the Macbook Pro to securely wipe itself? 2. After being securely wiped, how do I get Lion back on the internal drive of the Mac? 3. Do I keep the USB drive plugged in while it is being securely wiped or do I insert it after being wiped? * Thanks.