What is DeltaCopy

In general terms, DeltaCopy is an open source, fast incremental backup program. Let's say you have to backup one file that is 500 MB every night. A normal file copy would copy the entire file even if a few bytes have changed. DeltaCopy, on the other hand, would only copy the part of file that has actually been modified. This reduces the data transfer to just a small fraction of 500 MB saving time and network bandwidth.

NOTE: We now offer two solution for using rsync on Windows:

We recommend checking both of them to see which works best for you. Click here to see differences.

In technical terms, DeltaCopy is a "Windows Friendly" wrapper around the Rsync program, currently maintained by Wayne Davison. "rsync" is primarily designed for Unix/Linux/BSD systems. Although ports are available for Windows, they typically require downloading Cygwin libraries and manual configuration.

Features

Unlike "rsync", DeltaCopy is a only available for Windows and is tightly integrated with services available only on Microsoft platforms (NT4, XP, 2000 & 2003). Here is a list of features

Incremental backup - Copies part of the file that is actually modified
Task scheduler - Profiles in DeltaCopy can run based on a schedule
Email notification - Administrators can receive email confirmation on successful as well as failed transfers
One-click restore - Backed up files can be easily restored.
Windows friendly environment - No need to manually modify configuration files or play around with command line options.

reference: http://www.aboutmyip.com/AboutMyXApp/DeltaCopy.jsp