Answers

Pamela, there are a lot of window replacement options on the market. It's important to have a window which is designed for your region in the U.S. here is a chart by energy star which contains this info: https://www.energystar.gov/products/building_products/residential_windows_doors_and_skylights/key_product_criteria

If one is in your area, see if a local business manufactures windows tailored for your portion of the U.S. Avoid builder grade replacements, and try to work with companies which have been in business for 30+ years who can stand behind the warranties they provide. Always read the fine print, and make sure a remodeler will warranty the installation.