During discussions at a Microsoft Windows training course, one of the pro-UNIX delegates stunned the class when he pointed out that Windows NT4 is so limiting compared with UNIX. He likened UNIX to a mechano set that has an unlimited number of tools that are simple, efficient, and, in combination, capable of achieving any desired outcome.
One of the Windows networking advocates retorted that if she wanted a mechano set, she would buy one. She made it clear that a complex single tool that does more than is needed but does it with a clear purpose and intent is preferred by some like her.
Please note that all information here is provided as is and without recommendation of fitness or suitability. The network administrator is strongly encouraged to perform due-diligence research before implementing any backup solution, whether free software or commercial.
A useful Web site I recently stumbled across that you might like to refer to is located at www.allmerchants.com.
The following three free software projects might also merit consideration.
BackupPC version 2.0.0 has been released on SourceForge .  New features include support for rsync/rsyncd and internationalization of the CGI interface (including English, French, Spanish, and German).
BackupPC is a high-performance Perl-based package for backing up Linux, UNIX or Windows PCs and laptops to a server's disk. BackupPC is highly configurable and easy to install and maintain. SMB (via smbclient), tar over rsh/ssh or rsync/rsyncd are used to extract client data.
Given the ever decreasing cost of disks and raid systems, it is now practical and cost effective to backup a large number of machines onto a server's local disk or network storage. This is what BackupPC does.
Key features are pooling of identical files (big savings in server disk space), compression, and a comprehensive CGI interface that allows users to browse backups and restore files.
BackupPC is free software distributed under a GNU GPL license. BackupPC runs on Linux/UNIX/freenix servers, and has been tested on Linux, UNIX, Windows 9x/ME, Windows 98, Windows 200x, Windows XP, and Mac OSX clients .
rsync is a flexible program for efficiently copying files or directory trees.
rsync has many options to select which files will be copied and how they are to be transferred. It may be used as an alternative to ftp, http, scp , or rcp.
The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network link, using an efficient checksum-search algorithm described in the technical report that accompanies the rsync package.
Some of the additional features of rsync are:
Amanda, the Advanced Maryland Automatic Network Disk Archiver, is a backup system that allows the administrator of a LAN to set up a single master backup server to back up multiple hosts to a single large capacity tape drive. Amanda uses native dump and/or GNU tar facilities and can back up a large number of workstations running multiple versions of UNIX. Recent versions can also use Samba to back up Microsoft Windows hosts .
For more information regarding Amanda, please check the www.amanda.org/ site. 
27.2.4 BOBS : Browseable Online Backup System
Browseable Online Backup System (BOBS) is a complete online backup system. Uses large disks for storing backups and lets users browse the files using a Web browser. Handles some special files like AppleDouble and icon files.
The home page for BOBS is located at bobs.sourceforge.net.