The text at http://windows.microsoft.com/en-ca/windows7/what-is-a-system-image seems to indicate that everything is backed up in a system image, however I am running a backup right now that was supposedly explicitly told not to backup everything. The backup process window says the following:
Contents: Files in selected folders and system image.
I basically specified only to backup my user folder (minus a couple of unwanted large folders). Is this backing up my whole drive despite what I told it?