GeekTech, I'm sorry to be the one to inform you, but as far as I know, there are no legal Windows XP iso downloads. If you know of someone who has the same version of XP as you, there's a chance that their disk will work, using your COA.
There are many brands of reinstall disks of XP also, that requires no key. Still, it has to match what you have. If it comes down to it, you may be able to get someone who has a computer shop to reinstall it for you.