Using OEM XP Professional Product Key

I am installing Windows XP Professional on a Compaq EVO W4000 that has a legitimate XP Professional Product Key sticker on the side of it. I do not have the OEM installation CD that originally came with this workstation. My goal is to be able to install XP from another CD and use the product key from the sticker. Is this possible? If so, how do I accomplish it? I’ve tried entering the key from the sticker during install and it won’t take it. Please advise.