Files synqing on multiple drives

Hi There, I have come back to win bbs after searching google.
I am sorry if this is a simple question, but I cannot find an answer.
here is the scenario.

In one room I have an hp laptop with external esata drive and additional external usb drive.

Due in the past to almost losing all my documents I admit paranoia has set in -lol
anyway I have never used briefcase or am sure it is even what I need.
but basically I would like something to switch on overnight for example and it just update files that have not yet been copied to external drives etc.
i.e synq all 3 sets of files and make sure there are 3 sets, without having to copy everything, everytime

any recommendations please?

best
Danny

the system involved is win 7 premimium 4gb