Long story short- Being the nerd that I am, I spent a lot of time at the local lumber yard crunching numbers and prices on all the different R-values, double vs. triple panes, special coatings, etc. What I determined was that it would take me over 70 years to re-coup the cost of triple panes by the small increase in r-value that it provided over the coated double pane. Don't sweat your windows too much, Guy. The door that I replaced was only 34 years old.
![Wink ;)](./images/smilies/icon_e_wink.gif)