EISA configuration HD

My mother had an old computer running Win 3.1 that hasn't been up and running in years. We've recently built her a new computer and wanted to bring the HD from her old computer over as an external drive so that she can get all of her docs and photos off of it. Plugged in, Vista recognizes it, but it doesn't show in explorer. In disk management it showed an EISA configuration and at first I thought that was it. But unplugged, that drive still shows in disk management. So I guess that's not the drive. When I go into device manager with the HD plugged in, it shows that it's there and working properly, but I still cannot see it in explorer or under disk management. Any ideas as to what's going on and how to access the files?