SP2 won't install

Hi!
I have Windows XP on my computer and want to install SP2. I used the Express install system (since there is only one computer to upgrade). The download went smoothely but during installation it said that SP2 cannot be installed since my OS was not a legal one. Now I know mine's a legal installation but I can't find a way out of it. Is there a way to bypass the checking?
I don't live in any major city so I don't have a Microsoft Customer Support Centre here as well.

PS: Please do not suggest Network Installation. It will take a year on my Dial up.

I sounds like your copy of xp has not gone through the authentication process. Once completed sp2 should install properly.

Another issue is that some have experienced problems installing sp2 until they uninstall sp1.

i did the authenciation thing again and SP2 installed flawlessly... :) thanks for your help...