I have had this issue before and it turned out I was using Windows XP Pro Corporate edition, I had to use our corporate license code as opposed to just standard Windows XP Pro license. There is several different flavours on XP out there. This article should get you started on the right track: http://www.microsoft.com/licensing/resources/vol/volkeys_winxpsp1.asp?SD=GN <http://www.microsoft.com/licensing/resources/vol/volkeys_winxpsp1.asp?SD=GN&LN=EN-GB&gssnb=1> &LN=EN-GB&gssnb=1 -----Original Message----- From: Herchenbach, Jim [mailto:jherchenbach@xxxxxxxxxx] Sent: 11 December 2003 18:41 To: windows2000@xxxxxxxxxxxxx Subject: [windows2000] xp question OT I just purchased 6 new liecenses of XP pro....went to install it, and now when I try to install sp1, I get an error stating that my xp number is invalid...blah blah blah...please contact your vendor or microsoft antipriacy devision. ok, i know my license is valid, the only thing i can think of is that I incorrectly put in my code. Where can I check this on my PC/registry? tia Jim