I'm sure there is software available out there in the opensource world. I recommend checking out the following thread:
Learn the DD command
This is a very powerful command that is built into linux already. This will allow you to easily make backups of your system. Another way to make backups would be to use tar to make and compress your backups.
As far as what to back up that is for you to decide. Information that would be important would be the configuration files in /etc the data in the /home directories and any logs and such under the /var directory. Hopefully this helps!
