Most likely your house has double glazed windows - I only see single-glazed windows in antique wooden windows these days (but perhaps it's different outside of New England).
Good triple-glazed windows are expensive, but there are some vinyl triple systems that are reasonably priced. Anderson and Pella both have triple glazed options, for example.
There is also a relatively inexpensive (compared to imported European windows) option for tilt-turn windows now available:
http://logicwd.com/
I haven't installed them myself, but I've bought other systems from that vendor and have been happy.