How to make a hidden partition visible?

Here's how my hard drive is partitioned:

Recovery Partition 21 GB (primary partition)
C: 101 GB (Primary partition)
D: 141 GB (logical drive)
E: 141 GB (logical drive)
F: 190 GB (logical drive)
SYSTEM: 100 MB (primary partition)

The Recovery Partition is empty, hidden and no letter is being assigned to it. I want to use it to save an image of my current state of Windows. But it is undetectable to any Windows software.

Also, what is the difference between a primary partition and a logical drive?

Answer:

• Right-Click "Computer", Click on "Manage" (you need Admin rights for that!) and select "Disk Management" in the right area of the upcomming window.

• Right-Click your hidden partition and click "Change Drive Letter and Paths..."
  
  
  
  Click "Add...", select a drive letter and click "OK" in both of the small windows.
  
  A primary partition is the a partition on a harddrive. You can create up to four primary partitions. When you want to create more then four partitions, you have to create 3 primary partitions and one extended, which is a workaround to create more partitions. All further partitions created in the extended partitions are called logical drives. Booting is only possible from a primary partition.
  See also: http://windows.microsoft.com/en-us/windows-vista/What-are-partitions-and-logical-drives
  
  
  Edit: Seems like Windows only allows 3 primary partitions. Might be so to prevent users from creating 4 primary partitions so they don't have to delete one partition to create an extended one. Windows 7 only allows the fourth partition to be an extended partition.
  
  
  
  
  Thanks to superuser.