Even though most folks out there buy a product that promise energy efficiency and major upgrades they somehow don't end up much better than the older windows the home owner had before. Some window installers out there buy a factory outlet window that probably came from a major production facility in Asia.
The installer to make as much money as possible will purchase the cheapest factory outlet and grab the warranty sheet that comes with the specs. The specs wont make to you but the warranty might. With a factory outlet window the installer will find the window that fits closest to your frame along the inside. With the rest they will jam in the window with pine wood and jam is it to create a tight fit.
This is where the first trouble may pop up if the installer jams the pine to tight or miss measured the window and as a result the window bows and airways are created. I have seen some installs where the window could not even open as a result of a window that was to big for it's frame. you may think that putting a window that was to big for it's frame sounds like a silly thing to do but a second of a error in measurement and the installer is trying to decided whether he or she can fit a window only a quarter inch to wide or pay for a new window.
The best method of window replacement is starting with new windows that are made for your home to fit the frames of your home. The ability to choose the style of opening may be important and this choice is sometimes limited when you purchase a factory outlet window. Do not bother getting new windows if you are not getting Low E argon. without the windows are not much better than what you have got even if they are double glazed windows.
Windows are pretty quick to install so don't get worried if your entire home can be done in one day. Stick with vinyl frames, although there are window companies out there that have wooden or aluminium frames they mostly deal with heritage homes and repair work. Opening styles in these situations are also a issue. Patio doors are included with everything I have mentioned so don't treat them any different