(First of all I have to mention that I am new to posting, just posted yesterday for the first time and received a ton of respnses that solved the problem right away....this is a great community for a MacAddict like myself...THANKS!) I have a new iMAC 24" that has about 250 Gig of stuff that has been transferred from my old iMAC. I hooked up my external drive to run TIME MACHINE for the first time last night before going to bed thinking it would take hours to xfer all of that info to the external. I started the back up and in about 2 minutes it said that it was finished. I really don't get it...how does it work?!?!? Does the external REALLY have all of the 250Gig of stuff on it now? Confused and interested... thanks!