You can get it now from Windows Update by clicking to this Microsoft Download Link
The latest service pack is really mostly a bunch of bug fixes all rolled up into one package but I have found on all of the PCs that I have installed it on that it seems to have sped them up, not a lot perhaps but still the operating system is a little faster. The other great thing about the new Windows XP Service Pack 3 is that now we can do installs of Windows XP a lot faster. The last few installs that I have done have taken about three hours because even with an install of Windows XP with Service pack 2 there are still about 92 updates as well as that huge Internet Explorer 7 change.
so I can rejoice to this Service Pack upgrade for Windows XP today but this will probably be that last one as Microsoft will now start pushing hard to get rid of Windows XP in favor of Windows Vista.
By the way There is still some life left for support of Windows XP support will go on for a few years yet. Mainstream regular support will go until April 14, 2009, after that date Windows XP will begin its “Extended Support” period that will last for 5 years until April 8, 2014.