The *bleep* you say?! It is too correct! I've use the exact same download to install SP3 onto two other PCs and used it to slipstream a Home and Pro CD. It's only giving me this BS on (of course) the last XP Pro SP2 PC I have to update. (All were installed from SP2 Pro slipstreamed or Home with SP2 already on from OEMs.)

I've searched yonder intarweb with Google and come up with nothing useful, just vague hints that there might be some process that has to be running, which isn't. (And of course every possible manglement of my search Google could come up with instead of EXACTLY SP3 "update.inf file is not correct".)

You might look here:

http://support.microsoft.com/kb/946938

It applies to Server 2003 SP2 but will also apply to WIN XP.

HTH

Nope, that registry entry is fine. Next?