Vice Versa is a great peice of software so long as both end points are Windows machines, or you just want to mirror a drive to another. You can find it here: http://www.tgrmn.com It can also do one-to-many replication, and real-time replication (this is what I use it for mostly). The real time optin is nice as it listens for file change notifications and syncs as needed.

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