I think the best way to backup your documents it to use 3rd party software like Norton Ghost or Acronis True Image. They are not free but I think you won't find better solutions. I prefer True Image for its price and its features. In your case True Image is better because it can store backup images in network (I'm in doubt if Ghost can do this). True Image has a scheduler that will allow you to perform backups as often as you want. Good luck!