Win Xp Key I Have An Activation Key For Win Xp Pro But Not The Disk How Can I Download Win Xp Pro?

I have an activation key for win xp pro but not the disk how can I download win xp pro? - win xp key

Windows 2003, I pulled my CPU and I thought I had a backup since my CD is empty, but I have a valid activation key. Where can I get Win XP Pro. I look at the page, but I still can not even find a download