Microsoft Windows XP Service Pack 3 (SP3) provides new proactive
security technologies for Windows XP to better defend against viruses,
worms, and hackers along with increased manageability and an improved
experience for users.
Microsoft Windows XP Service Pack 3 fixes
a range of bugs in Windows XP. It doesn't matter what XP updates you
have previously applied to your system, SP3 will update any unpatched,
partially patched or completely updated system (it includes all
previously released patches and updates). XP SP3 fixes the security
holes so you won't get attacked.