I just saw over at Warp2Search that Windows XP Service Pack 1 has been released, supposedly. As far as I know the patch was supposed to be released on the 9th of this month. Maybe someone discovered the link early. Anyway it doesn't matter, the download locations below are straight from Microsoft servers so you should be right to give this one ago without too many dramas.
Have fun; let us know about your results for the Service Pack in our Windows XP Forum!