I do nightly backups of my system image on my desktop computers.
It has saved me countless hours of grief and aggravation more than once over the last year or so
On Wed for example I couldn't start Windows 7 so I booted using the F8 key and did a system image restore. It took about an hour of mostly unattended time and worked perfectly.
I highly suggest using backup to create a system image as often as is consistent with the usage and of the computer and type of activity performed on the computer.