You can run rsync on Windows as well. It is entirely command line controlled.

You can get rsync for Windows as part of Cygwin's toolkit:

http://www.cygwin.com/

If all you want is rsync though, this might be better (it also looks like it deals with some of the issues of getting rsync running as a service on Windows):

http://www.itefix.no/cwrsync/

Here is the manual page for rsync:

http://samba.anu.edu.au/ftp/rsync/rsync.html