And what do we get for our efforts? We get a disc that can start our computer. In fact, it starts out like a Windows 7 installation, except even more slowly (if you created a CD rather than DVD). It asks you to select a currency, time format, and keyboard layout. Then it goes looking for Windows installations to repair. If the disk image is on an external hard drive, it might not be noticed unless you click the "Load Drivers" button.
This will then take you to recovery options screen, where you'll have your choice of performing startup repair, system restore, system image recovery (from the source you've previously saved), Windows memory diagnostics, or a command prompt.