Use Bootit NG (free 30 day trial) or PartitionMagic. Bootit NG will be able to image the hidden partition. Usually, hidden partition is used by crappy vendor such as HP to restore the OS. The stupid HP bean counters don't want you to own recovery CDs.
Proved to be a good software for the purpose as stated: http://www.soft32.com/download_151.html (Partition Magic 8.0)
Note that you will not be able to image the hidden partition with PartitionMagic. Bootit NG combines a partition manager, imaging software, and boot loader into one package.