If it is that old then updating the Microsoft updates will take some considerable time. Although SP 3 is available for download, click here, and similar for SP 2 if you search. I don't know if the other updates will still be available via Windows updates on XP.
If not you would have to run Belarc, that program shows all the missing updates, then use Google to manually download them, a few at a time, and install. Could take a while.