Hi! I was looking for an external hard drive to backup my photos/music collection. I was hoping to stick with Western Digital in 1TB capacity. Do I have to buy one of their hard drives that says specifically on the box "For MAC" or can I buy any Western Digital Hard Drive. My concern is that it won't work with Time Machine. My thinking is that it is only formatted for Apple. You can buy any external drive and format it for use on a mac? Am I correct?