North Georgia Replacement Windows will make your window and door buying process simple and stress-free. You will get style PLUS energy efficiency with Infinity from Marvin fiberglass replacement windows. Infinity Windows utilize the patented Ultrex®process that combines the best in energy efficiency, durability, and beauty. … and don’t forget your doors – we offer a variety of custom and decorative door options. Whether you are looking to replace your main entry door, French, or back patio door, we have a full range of choices available.