AcomData make lots of external products. Some are encrypted ...
Can you show us the contents of sector 0? This will tell us what kind of OS and partitioning system was used, and whether the data are encrypted.
Depending on your version of Windows, you may be able to see the partition table and boot sector with Microsoft's Sector Inspector:http://www.users.on.net/
If you extract the above archive to the one folder and execute the SIrun.bat file, then this will generate a report file named SIout.txt.
Otherwise, you could use a sector editor to dump sector 0.
Roadkil's Sector Editor:http://www.roadkil.net/program.php/P24/Sector%20Editor
HxD - Freeware Hex Editor and Disk Editor:
DMDE (DM Disk Editor and Data Recovery): http://softdm.com/download.html