Serial Key Per Mount E Blade How Can I Find Out Cd--key Or Serial Number Of Windows Xp Which I Had Installed On My Pc ?

How can i find out cd--key or serial number of windows xp which i had installed on my pc ? - serial key per mount e blade

He had Windows XP installed on my PC, I bought six months ago, now I have lost a record, but I'm not for the care of his double and end-user license that can make personal copies of this CD. So, I just want to the serial I installed XP on my PC to know before my OS. Someone please guide me what should I do?