Download Windows XP SP3 installation CD on your computer from the Internet but if you are on a slow connection, Microsoft will ship the XP SP3 CD to your home for free.
As in Windows Vista, Window XP SP3 users can complete operating system installation without providing a Windows XP product key during a full, integrated installation of Windows XP SP3.
Windows XP SP3 is available through Windows Update and the Microsoft Download Center. The service pack will also be available to Volume License customers, TechNet subscribers, and MSDN subscribers.
Windows XP SP3 includes all previously released Windows XP updates, including security updates and hotfixes, and select out-of-band releases.
Windows XP SP3 may be just round the corner and is expected to include all hotfixes ever issued by Microsoft since XP SP2.