If the OS is corrupted, then you probably would not want to use a system image to restore you current install. But you might make one just in case.
The only way to do what you suggest, is to do a Repair Install, where you start the install from Windows and not booting to the DVD. Whether you can do this may depend on your system and if it is OEM or whatever. So for better recommendations, you might want to describe your system and what restore/install media you may have.