I copied my Home folder to an external HD yesterday, which took some time because it incorporates approx. 100 gigs. My questions is this..... If I drag that same folder to the external HD again today, I am presented with a dialogue box that states that the folder already exists and asks if I want to cancel the operation or replace the folder. If I replace the folder will it only copy over those files that are new and/or modified or does it literally start from scratch and copy all files over again?