I booted from the startup DVD and am running Disk Utility on the macbook I am selling to someone. I selected the drive and am dong a 7-pass erase on it. Is there anything else I need to do to make it so my information cannot be stolen? When I am done erasing, do I install the operating system for the new user (doesn't that ask me to register, though)...? So basically how do I make it so its like it just came out of the factory?