I have two 1TB external HD's that I use. One is my primary storage device (besides my laptop's HD) and the other is a backup of the primary external. When I backup external 1 to external 2, I basically delete everything on external 2, then copy it all over from external 1, using a second computer. I'm thinking that might not be the best way. What do you recommend? I have a Win8 laptop. I'm planning on getting a new 2TB (or larger) external, but this is what I have for now. Thanks!