If you have a Linux machine, Arkeia Software has a FREE USE Version that can be used to backup your WD Sentinel because it supports Windows 2008 as a client.I use my Sentinel as a file server so I backup the DX4000 and my laptop using CentOS 5.3 and Arkeia Free Version. The Free Versions supports backup to disk, but I also have a DAT72 tape drive for my critical stuff like tax and child support payment recorrds. LOL!!
Free Use and Demonstration Editions