How to change the product key of any windows operating system if you have already installed a key.

You can do it with WinKey Finder with ease.Although you can do it manually by editing some registry key but i think that its not a convinient method. So here is the link where you can donwload this tool and play with it. http://files6.majorgeeks.com/files/f06048518ff8de2035363e00710c6a1d/covertops/WinKeyFinder173_RC2.zip