PhotoStructure is designed to be a very safe home for the images of your life.
You should consider older hard drives, especially more than 5 years old, as fragile parchment that must be handled with care. Older drives will almost certainly have developed bad sectors — portions of the hard drive that no longer can store data reliably. By making copies, preferably to a new drive, or better, a RAID array in your new shiny NAS, we're not putting as much wear and tear on your old drive, and we're maximizing our chances to keep your originals in good shape.
Photo by Aaron Greenwood.