I always format the disc so that there is an operating system partition and a data partition, and teach users how to use it. Then I move the mail folders etc. onto the data partition.

I also try and get people to consider the Computer as a filing cabinet, with Windows explorer the means of finding stuff, and double clicking on files to open them - let the file determine the application.

That way I can back up the whole partition easily, and also restore the operating system without losing data. [which of course you have to do with windows periodically].