Belarc or Keyfinder, both are free for the download, to find the product key number. You can also connect to the internet, go to Windows updates and try to update the operating system. Microsoft requires you validate your copy of Windows. If it is legal, it should pass the test.
I bought a computer ( at a yard sale) that has windows xp on it. How can I find out if its has a legal cd key on it without calling ms. I know the cd key but no windows sticker is on the computer.I don't want to buy another xp cd If the cd key is legal. Can anyone help Thanks