System Restore saves information about Windows system files, programs, registry settings and other system information that Windows uses. They do not contain personal files, such as email, documents or photos.
Location of System Restore filesThe System Restore files are generally stored in a hidden and protected folder named _RESTORE folder in Windows Millennium and System Volume Information in later operating systems. It is located in the root directory of your hard disk. This folder is marked by the system as read only and hidden. It can be viewed only after making a few configuration changes from an Administrator account.
Why disable System Restore?System Restore backs up the bad with the good, hence as a part of malware cleaning it is advised to turn off and on System Restore to eliminate the presence of malware infected files in the System Restore points.
IMPORTANT: Remember to turn off and on System Restore only after disinfecting your computer, because an infected restore point is better than no restore point.
The following links show in pictures how to Turn System Restore on or off in windows 7 ,Vista and XP