If I buy a used mac on ebay that has a lot of software on it, but not the original disks (because they were lost ) and I need to re-install the OS or wipe the hard rive, how can I save these apps? Can they be dragged and dropped to a firewire drive and then reinstalled one the computer is reset with a clean OS install? How can I do this? I am a PC user, and this cant be done on a pc. Is it possible on a mac?