I have to agree with SheltieChe. When we call out to be quiet when dogs are barking at the door, a window or on lead we are actually percieved as joining in. Personally I would put a drag line on her and as soon as she goes toward the window I would pick it up and walk the other way encouraging her to come with me. Lots of treating for all movement away from the window including just a turn of her ear or her face but none for turning back. She needs more exercise and more stimulation in the house and outside. Take her somewhere that is less busy than the park and teach her to walk nicely on a lead. Put lots of sits, turns etc so she has to watch and think. Teach her the "watch me" command. Get her to obedience classes to get her used to more people and noise. Once you can get her to focus more on you when you are out at her quiet walking place then go to somewhere slightly less quiet and start all over again. Measure her food into a bowl and use most of it to train randomly throughout the day. If you get on top of it now and make no excuses for her barking at people then you should be able to get her to calm when she sees them. I wouldn't let her get to the windows at all at first. She has to earn the priviledge.
I was going to buy the stuff that you stick to the window, but my roommate was worried about how difficult it will be to remove it. Wax paper might be the perfect solution. If that doesn't work then I'll buy an x-pen and block off the whole window.