Check archives and/or do a search and you will find answers to your question. Although some of the archived posts have been deleted or censored you will find some answers.( Some rightfully so. My own posts included) The debates get nasty sometimes and the posts always seem to get way off the path of the original question and go on forever. This does more harm than good to both sides of the issue. Also check www.replacementwindows.com
a sister site.