A legal license is what is required. You have a couple of options as I see it.
1: Find a retailer still selling copies of XP
2: Call Microsoft and try to buy a second license for the computer with the pirated version
3: Forget Windows and install Linux
Apparently the person who gave me my computer used an unlicensed version of XP. I can't install any upgrades because of this.
I have a Windows XP disc, that was given to me by someone else a few years ago. I had no problem getting updates on that computer.
My question is........what is required for me to install the XP that I know I can update?