windows 7 has a built in system that you can use to create an image and a rescue disk - hit start, then type in backup, and open Backup and Restore - you will see 2 options when this opens up - create a system image and create a system repair disk - if you choose the image option plug in an external usb drive and push the image out to it; once complete create the repair disk. If you need to recover you just start the pc from the repair disk with the usb drive connected, once you select the language option you can select restore then select the image on the usb, Windows will do the rest.
If you want a 3rd party tool try EASUS Todo Backup (Free) - it is very easy to use and works like a charm.
Sid
November 2011