Having genuine software is the best way to get rid of virus, flaws and other nightmares. You need a licensed copy for example to install Microsoft Security Essentials.
If you want to change or update your windows product keys don’t use complicated methods, go to Microsoft and use the utilities they have for this.
It works on Windows Vista, Windows XP and Windows 7.
1. Go to this web page:
select your operating system and follow the instructions.