The above question might sound rather open ended but I'm thinking of buying one of the western digital passport drives to use for backing up my Macbook Pro's 120gb disk. I am thinking about how the disks lose capacity after formatting etc so would I be right in saying that if my 120gb disk was full, the 120gb passport drive would still be able to fit everything on to disK? I don't think il ever come across that problem but just wanted to check it out as my method of backing up is to backup a complete disk image so i definitely need to ensure that 120gb will be enough. Thanks