I'm here to help! If you purchased a computer with Microsoft Windows XP, and it is genuine, then you will find that setup on the computer. Open Local Disk (C:), and if you see one folder named "i386" then you have the setup. Open this folder. Open the application "winnt32.exe" to start the setup. Type in your 25-character product key. You can find this product key in the outside body of your comp. Then install Microsoft Windows XP by the setup, or, if you didn't find that folder, purchase a fresh copy of Microsoft Windows XP before August!
if anyone is stuck with an original windows xp cd and lost the key, this is how to retrieve your key from the disk >>If you have lost your Microsoft Windows XP/Windows Vista Serial key number then here are some solution to retrieve the serial number.For windows xp users if you have your original CD with you then Insert WINDOWS XP CD into the player and Just explore the cd to find a folder called i386 where you will have a file unattend.txt.Open the text file and you will find the CD serial key of your Windows Xp when you scroll to the bottom!
you can get a registration code extractor. it will search your OS and tell you what registration code is running windows. I am not sure what the link is but you can search google with the keywords "extract windows xp registration code"