Microsoft has recently released Service Pack 3 FINAL for Windows XP to the public. Windows XP Service Pack 3 (SP3) includes all of the previous updates, hotfixes and security updates to date, rolled into one simple package. It should been noted that Windows XP SP3 does not include Windows Internet Explorer 7. However, SP3 does include updates for both Internet Explorer 6 and Internet Explorer 7, and it will update whichever version is detected on your computer.
Installing Windows XP Service Pack 3:
I have personally upgraded quite a few Windows XP computers to XP Service Pack 3 and have had nothing but good luck so far. However, since SP3 is still in beta and not yet a final release, there may be bugs that have yet to be found. Service Pack 3 Final has been released and the Official Microsoft download link updated to reflect this.
Proceed with caution and install at your own risk.
You can download the stand alone Windows XP Service Pack 3 executable directly from Microsoft HERE
Additional information about Service Pack 3 can be found direct from Microsoft HERE