Are you familiar with the MusicPad Pro? It's a 12.1" screen tablet purpose built for a music library. It's a discontinued product now, and your requirements for Word file editing probably count it out, but it seemed really well thought out. If what you're doing is chiefly displaying words and/or chord charts, you've got probably more flexibility in solutions, but if you were depending on actual scores and relying on having a lot of them available at any one time, it was about the only game in town for many years.

If I were to guess at the reasons for its demise, it's that the company was just a few years ahead of its time. The market for a many hundred dollar piece of equipment just to manage sheet music is probably terribly small. Now that everyone has a tablet or is contemplating purchasing one, it makes a lot more sense to sell that kind of solution as a software app, which many companies are in fact doing.