Windows Image Backup With Format Option

When restoring from a Windows Image Backup (made from the control panel in Windows 7) you get to page
where you can check

::Format and repartition disks
Select this option to delete any existing partitions and reformat all
disks on the computer to match the layout of the system image.

OK! Suppose I haven't changed my partitions so there's no reason to restore the layout. Would there be any
reason to check this Format option? (1) Could the system/computer in any way be better off as a result of
reformatting? (2) Isn't the C-drive reformatted automatically?

For example, assume I have a pristine WindowsImageBackup and am restoring as a result of malware put on
the computer after the windows image backup was made. (3) Won't the malware get totally nuked no matter
whether or not the partitions are reformatted?

 

Restoring from the image you created should overwrite any information currently on the disk and restore it to it's previous state (ie. sans malware).