How do I recover data from a HD that can be seen in Device Manager but not accessed?

I have a Windows XP Pro desktop with a Western Digital 160GB SATA drive that will not boot but can be seen in Device Manager when removed from the host machine and connected to a different PC.  Device Manager reports the HD is working properly, but the HD cannot be accessed.  The desktop PC in question had been running AcomData backup software connected via USB to an external HD and set to backup every night.  Interestingly, the external backup HD now also shows the same symptom -- that is, connected to another PC it can be seen in Device Manager but cannot be accessed.  Both HDs in question spin up and both can be seen in Device Manager, so I have no reason to believe there has been a hardware failure.

Please recommend a solution, ideally one that might be software-based ... some way to access either one of these drives, which contain irreplaceable QuickBooks files required to run my small business.
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you can also try booting from the live KNOPPIX cd (free) to access your data :
noxchoGlobal Support CoordinatorCommented:
Try to use File Transfer Wizard from Paragon made software. It is free and up to date:
Download it and execute the exe file. It will burn the CD and let you boot your PC from it.
Also, I highly recommend their backup solutions which never let me down for several years already.
were you successful ?   (i like some feedback...)
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