STEP1:
Click "Start" and go to "Run." Enter the following string: %systemroot%\system32\oobe\msoobe.exe /a
STEP2:
Click "Yes, I want to telephone a customer service representative to activate Windows" and then click "Next."
STEP3:
Click "Change Product Key."
STEP4:
You will now be able to enter the valid license serial number for your Windows XP.
STEP5:
Press "Update" and close the window.
STEP6:
Restart your computer. Your Windows XP version now has its new serial number. Just do this to the rest of your computers if you own a computer shop.











