wasn't going to speak up, but i will in case anyone is considering thermotec. (they have the ads for free window, you just pay install on tv here in colorado and probably elsewhere). if you have standard size windows, avoid them. the windows will not make your home more energy efficient as they claim. i went from single pane glass windows and poorly installed double (you could feel the air blowing almost unhampered from around the windows) and there was no difference in my bills (yes, i was comparing usage).
if you have odd sizes, they may be worth it if you are looking for a window that actually slides up and down (unlike the doubles i replaced) and have looked into having custom sizes made (i don't have one normal sized window in my house.
to have one double large window (they actually made it into two windows; lower side sliding with a thin solid window across the top), three large windows, two med windows, two small windows and one custom mini window installed on my house was 6k. the people that do windows for thermotec are local contractors (i can see my contractors house from where i'm sitting right now), so quality there depends on the contractor (i was extremely pleased...5 hours, no leaks around the windows and they cleaned up).
i now have windows that slide up and down and drop in for cleaning, new screens that also slide out of the way and they look nice, so for me it was worth it.