Well, I went ahead and started the eBook Library without plugging in my device. It asked if I wanted to update the software, and I said yes. I got some kind of a registry error after the installation was finished, but I was still able to open up the program, connect my Reader, authorize it, and "purchase" a half-dozen of my free Classics.
I'm downloading them now and we'll see how that goes. I'm not sure what happened before but it seems to be okay now.
I did not do the DEP thing; I'm going to wait and see how this goes.
Thanks so much for your help and encouragement!