Ckorody,
Thank you so much for taking the time to explain all of this. That was very thoughtful of you.
First, it would seem that the easiest way to do this might be to connect the external hard drive to an old laptop that we don't use much now, and then we wouldn't need to buy the SB or Airport Express, correct? If she's downstairs, we won't be able to connect a cable from her to the preamp upstairs. Listening between floors generally doesn't present a need to control volume, so maybe she could simply turn on the music in the morning and let it play all day.
We're in the process of starting a new business, so I don't have much time (or desire) to play around with this. I'm hoping for a quick and easy setup. I'll be ripping much of the tunes from a friend's CD, as he, my wife, and I share musical tastes, and that way we both have a backup drive in case of a meltdown.
I will look into some of the suggestions you mentioned regarding file management. We don't have iPod's (imagine that), and won't have a use for them anytime soon. Other than the older laptop, all of the other computers in the house are brand new, and our business is web-based, so we should have sufficient RAM, I would hope.
I'll read through your post again and see what else I might absorb. Thank you again for taking so much time to respond.
Regards,
Howard