If you want to make an ISO backup of your important disks, then Linux is a good place to do it.. As it has all you need built in!
From a Terminal window simply type:
mkisofs -o /tmp/cd.iso /tmp/directory/
Obviously replacing the path to the ISO and the path to the directory with where you want to store the ISO, and the path to the disk you want to backup.
It really is as simple as that! If only Windows had that facility built in!
