To start if anyone is kind enough to reply to this thread please do not use abbreviations or very technical words as I am completely non technical, thanks. I have an iMac and need a backup device. After mulling over my options (for a nontech person) I have decided on a WD My Book Essential, probably the 500gb. Now I want to use it to backup my Time Machine to and also mainly photographs, home movies and documents. Is a hard drive like a filing cabinet? Is it like one big filing cabinet unless you partition it? ie Could I partition my WD into say 4 compartments? Would this mean that I could give one compartment to TM and when it was full up it would override the first backups? If I am understanding this all correctly then how do I partition it? If I have got this completely wrong could someone please tell me how to work this thankyou? I bought an Iomega external but it died after 5 weeks.