Microsoft Windows Server 2003 Service Pack 2 (SP2) is a cumulative service pack that includes the latest updates and provides enhancements to security and stability. This service pack is available for Windows XP Professional, x64 Edition.
Below is a link to a post on bleeping computer that has a link to one, scroll down to the post by Mike_Walsh near the bottom of the page. I recently used this one to recover an old HP (2003 vintage) that had a hard drive failure. This machine was used for a video camera/monitor setup on the production floor of a client, and was not connected to the LAN or the internet in any way. I scanned it with Sophos and Malwarebytes and it came up clean and has worked without issue for about 4 months now. I will warn you though, when you transfer the iso to a bootable USB, do not change the volume label that Rufus auto generates. If you do, it will not self activate correctly.
Xp Professional Iso Download Microsoft
Windows Xp Pro Iso Download
If you feel uneasy with this, you can still purchase a full retail version here, where they will send you a download link about 10 minutes after purchase.