Greetings --
Are you trying to install Service Pack 1a and getting the
following:
The Product Key Used to Install Windows Is Invalid
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q326904
You need to purchase and use a _legitimate_ full retail copy of
WinXP Pro to perform a repair (a.k.a. in-place upgrade) installation,
using the new CD and Product Key.
How to Perform an In-Place Upgrade of Windows XP
http://support.microsoft.com/directory/article.asp?ID=KB;EN-US;Q315341
Remember, you should also report whomever sold you the pirated
software to the pertinent law enforcement agencies; you've been
defrauded.
Bruce Chambers
--
Help us help you:
You can have peace. Or you can have freedom. Don't ever count on
having both at once. -- RAH