I've read all the exhortations, mostly in Old House Journal, about keeping up old windows, but I couldn't possibly see how this would benefit the home in any way. Most of the sashes were rotting - and there was absolutely no isulation to be found.
We bought nice new fir windows from Loewen. They're really nice, and of course double paned. Once the trim went back on they started looking a lot better, but it was looking sketchy when there was expanding foam coming out everywhere.