How to Update windows xp sp2 to sp3 (from service pack 2 to Service pack 3)

Updating Windows XP Home Edition , Windows XP Professional Edition, Windows XP Service Pack 1 or Windows XP Service Pack 2 is easy just use automatic updates or you can visit Windows Update at http://update.microsoft.com.

But the best way is to download the installation package from http://www.microsoft.com/en-us/download/details.aspx?id=24 

This installation package is  intended for IT professionals and developers downloading and installing on multiple computers on a network but it doesn't matter if you install on single pc or more..