So I tried using TM for the first time today with my 250gb Western Digital Mybook but it wanted me to reformat the drive. Well I obviously can't do that because I already have about 60gb of important files on my external that are no longer on my computer. Another question I have is how does backup work? If my laptop is using 50gb, will my external HD consume an additional 50gb each time it backs up? So in theory I'd only be able to backup 3-4 times? In other words for example, will I have 3-4 copies of the same picture or music file? OR does it overwrite, so that I'll only have 50 gb used on my external at all times. What I don't understand is, what's the point of using Time Machine if I can manually back up my system whenever I want (just copy and paste the Macintosh HD into my external HD). People seem to rave about Time Machine. But IMO time machine seems time costly and inefficient. Convince me otherwise. Tell me what I need to do. I'm all eyes and ears. Thanks.