Original windows are a key feature of your home, and your neighborhood. Saving originals is a better value than most replacement options, and the windows you have could last over 100 years more, something no replacement window will do.
NOT JUST PRESERVING THE HISTORY
In Greater Southeastern Pennsylvania it is hard to find any building more than 150 years old, but every home built before 1945 has windows that, if left in place, will be considered historic in just 25 years.