The last Service Pack for Windows XP

This service pack applies to Windows XP only.

To determine which version of Microsoft Windows you are running:
1. On the taskbar at the bottom of your screen,
click Start, and then click Run.
2. In the Run dialog box, type: winver
3. Click OK.
A dialog box displays the version that you are running.

To download the final release of Windows XP Service Pack 3 please click the link below.
XP SP3 (316MB)
Select Run to install it right away or select Save for later installation.

Minor security and reliability updates are included in the package.
This is the last service pack for Windows XP as Microsoft have shifted its focus to Windows Vista.

Good to know dates about Windows XP:
Microsoft will stop selling Windows XP on January 31, 2009
Windows XP Life-cycle

Microsoft will trim down support for XP on April 2009
Windows XP Support Life-Cycle