The Ultimate Free Windows Toolkit
Subject:   Robust File Copy aka Robocopy
Date:   2006-06-14 17:57:15
From:   jellings
This has to be one of the best. Not only is it free, but it is also from Microsoft!

Use it to maintain backups in a variety of ways, from automated mirroring to incrementals to whatever type of backup you need. It is now bundled with the Windows Server 2003 resource kit,

I wrote a super brief quick start on using it here: