If you have a mac you should call 1-800-MY-APPLE for tech support (you get this for free for 90 days, and if you bought applecare then you get it for 3 years) and ask them about setting up a time machine backup for your mac. Time machine is awesome, when you plug in your external hard drive it backs everything up on your computer and saves everything (files, settings, etc.) Fortunately, I have only had to use this a couple of times and it saved me a ton of headache. If your hard drive ever crashes, which ever drive can, all you have to do it plug in your external hard drive and everything gets restored to how it was (all programs, files, settings, everything) Here is the link that explains it to you
http://www.apple.com/macosx/what-is-macosx/time-machine.html
