I would like to clean all my disks (format C). My question is how to copy the EE2.0 with all projects in the easiest and fastest way?

I would suggest dropbox, easy and very good for that. Upload it onto your personal dropbox, when you've formatted install dropbox and voila, there's your files downloading again

You could set up the server on another computer and upload your project, or just copy the Projects folder to a USB drive. It's probably best to do a fresh install of EE once you are back up and running-it's the projects folder that is the important part.