if you did not have any service packs on your install cd, then you will have to install sp2 and then sp3 and if you have an HP then you will have to install a patch
before installing sp3
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courtesy of tricky 300
Windows Updates no longer works until you have service pack 3 installed. To overcome this problem you need to get to SP3 manually.
Verify your current service pack level...
Hold down the Windows key (between Ctrl and Alt) and hit the Pause Break key
Examine what is listed in the System: section regarding your service pack level
Also, make a note of your processor type in the Computer: section (see later)
If there is no service pack level designated, first you must download SP2 from...
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=28
...and then run the downloaded program to install SP2. You can ignore the text that says that it is for network installations and also ignore the text advising Windows/Microsoft Update if only updating one PC.
As an alternative to SP2 you could download SP1A (xpsp1a_en_x86.exe) from…
http://slug.ceca.utc.edu/ftp/pub/windows/patches/winxp/
…which a fellow contributor Daavee found. It is half the size of SP2 so should be quicker. However, as you can see, it is not a Microsoft web site.
Once you have done that, or if you were already at service pack 1, 1A or 2, you can install SP3, but before you do, read this article…
http://support.microsoft.com/kb/950717
…and if your PC is an HP Pavilion, Presario or Media Center and has an AMD processor (see above) you need to install this patch before installing SP3…
http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?cc=uk&lc=en&dlc=en&softwareitem=pv-60484-2
Install SP3 by downloading and running from...
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=24
…again, you can ignore the text that says that it is for network installations and also ignore the text advising Windows/Microsoft Update if only updating one PC.