I have a MacBook 4,1 with OS 10.5.8. I also have a 500GB external drive made by Seagate, called a GoFlex. Over 400GB of it is free, and it has the ability to be accessed by my iPad over wifi, and I also use it to back up files from a Windows laptop. On my MacBook, there are a few folders that I would like to back up on a regular basis to the GoFlex. The main problem is that Time Machine does not recognize the GoFlex at all, even though the drive's icon appears on my MacBook's desktop. Furthermore, I don't want to reformat the GoFlex in any way because I'd like to retain its usability with those other two devices. So in short, I need to either get Time Machine to recognize the drive and not reformat it, or I need some alternative. Does anyone have suggestions?