KenTUCKY

I installed Windows XP Pro using a borrowed CD to see if it would work on my older PC. It appears that it is going to be okay, but now I need to activate using a license code. Can I purchase an OEM license from an online vendor and use that code to activate, given that the CD that I used was not an OEM version? I don't want to purchase a license that won't work, nor do I want to have to reinstall from scratch again.