In addition to what the others have said, it's important to point out that the FRAME should be insulated too. Usually, it's a foam core.
I've never heard of an insulated window in an 'older home' unless someone put a modern, insulated window IN and older home. By nature, 'older homes' (relatively speaking), weren't built with insulated windows. Storm windows are usually separate from everything. They're, well, hung when there's a storm coming. Soooo, they should be easy to hang, and easy to remove. A lot of times, they're hung in winter to give the illusion of a double-paned window. (The storm window does reduce the air infiltration effect, but not that much.)
It would be best to talk to a professional to see what's involved. He should be able to tell you what effort it would take him to fix the windows. Other than that, w/o seeing the problem, it's hard to say from here. My best to ya and hope this helps.