Saving files on server - Switching admin panels

I have a dedicated server with Rackspace and I am switching admin panels from Webmin to Plesk. I must store all of the files that are currently on the server before we make the switch as we must redo the entire server. I need someone to get all of the files currently on the server and help me go through and figure out which ones I will need and install them back on the server once Plesk is uploaded to the server. I am developing new software for most of the sites so the main thing I will need to keep from the sites currently on the server are the design files. I need this done as soon as possible. Thank you for your bid.