Previously mentioned as being used to completely restore a broken system using partition images was Clonezilla, so it seems like a good idea to post up a short guide for using it!
The First Step: Download the iso from here, you're looking to download the one marked as 'stable iso/zip'. You can then use a program like Infrarecorder (Windows) or K3B (Linux) to burn the iso image to a blank CD. Alternatively, use USB Startup Disk Creator (Ubuntu - System > Administration) or UnetBootin (Windows) to create a bootable USB drive.
The Second Step: Check your bios settings to ensure that your USB or Disk Drive is listed above your HDD in the boot order, else Clonezilla will not initialise upon bootup.
The Third Step: Have your backup medium ready, be it USB Stick or External Drive, but do not plug them in yet. Boot the computer, you should be presented with a menu looking just like the one below:
Rest of the guide after the break: