Differential Backup

http://www.handybackup.net/differential-backup.shtml
Handy Backup™ is a family of data backup and disaster recovery software for computers working under Windows 7/Vista/XP/2000 and 2008/2003/2000 Server operating systems. It is available in three editions designed for individual PCs: Standard, Professional and Full, and a network backup edition called Handy Backup Server. The editions have different sets of features and are targeted at different market segments.