Hi, I have a MacBook Pro running OS X 10.5.8. I just purchased an iPhone 5 and found that the iTunes is not compatible and in order to upgrade iTunes, I need to upgrade my operating system. Question #1, Do I need to upgrade all the way to Mountain Lion or will an upgrade to Snow Leopard suffice and #2, I need to get an external hard drive to back up my system. While looking at them online at BestBuy.com I noticed that some will work with only Leopard and Snow Leopard while others work only with Snow Leopard, Lion and Mountain Lion. Are there any out there that would work no matter what OS I have?