|Service Pack 3. That is the latest service pack Microsoft released for WinXP. You need it installed to download any updates.|
I am not currently using a WinXP computer and can't recall where to find that information. I really doesn't matter right now.
If memory serves me correctly you can get to the restore screen by clicking on the Start orb then help. The option should then show. You may need to change the month as well as the date. Any restore point that is available will be highlighted.