Download Windows XP SP3
Windows XP SP3 has a special installation package for IT professionals that is available through the official link of Microsoft
http://www.microsoft.com/...
Step 1: Click on the "Download" button on the page and choose the option "Go"
Step 2: To be able to save the program to your computer, choose the option "Save as" and choose the path directory on which you want to save it on your computer.
Step 3: If you wish to install the program from its current location, choose the option "Run this program from its current location" or click on "Open" to open it from anothrer location
Note: This program is meant for a network, do not do this if you have to update only one computer. I will suggest you to use Windows update from the Microsoft website.