The easiest way to recover your operating system in case of disaster is by cloning it once a week to an external disk. You will save lots of time tweaking the settings once again if you need to reinstall your operating system.
Main Linux live CD to clone a hard disk
CloneZilla: Clonezilla live is suitable for single machine backup and restore, Clonezilla saves and restores only used blocks in the hard disk, this increases the clone efficiency. This live CD to mirror your hard disk can be a bit overwhelming for newbies not used to Linux.
SystemRescueCD: This Linux live CD is normally used to recover data, you can use it to backup data from an unbootable Windows computer not able to boot anymore, as long as the hard disk is still working, you will just need to mount the partition.
UltimateBootCD: You can use this Linux live CD for hard disk cloning using some of the tools it has, such as CopyWipe, g4u, HDClone, partimage and others. You can also use this Linux live CD for data wiping as it includes hard disk wiping tools such as Darik’s Boot and Nuke (DBAN) and HDDErase.
PartedMagic: This is mainly a Linux live CD used for partitioning but it also includes CloneZilla from the command line.
GRML: For the advanced Linux user, this Linux live CD based on Debian has been designed for the Linux system administrator comfortable with the command line, GRML provides security and network related software, data recovery and forensic tools and many text tools.
Computer Forensics live CD to clone hard drive
Caine: Ubuntu based computer forensics live CD, mainly used to acquire data of a suspected criminal computer but also useful as a back up live CD. User friendly graphical interface.
Kali Linux: Kali Linux is a versatile penetration testing distribution with 300 open source tools to test your network for vulnerabilities before a break in or do a post mortem after an intrusion has taken place.