A statement in Exchange 2007 SP2 release notes that has confused a lot of admins trying to install SP2 is “You must uninstall all interim updates prior to installing Exchange 2007 SP2”.
I have seen too many people asking questions about this in forums. The main query is whether the update rollups (UR9 being the latest) be uninstalled manually before running SP2 setup.
The answer is NO! Interim and update rollups are two different things. Interim updates are custom made fixes for companies who have been involved in a Microsoft support case. This is NOT to say that everyone who has ever opened a case with Microsoft should uninstall update rollups.
Microsoft support hands out interim updates (fixes) to solve certain issues which comes their way through support calls. I would say that those who have installed interim fixes will know about it and those updates need to be uninstalled before installing SP2.
The update rollups, which are available free of cost from the Microsoft Download Centre, DOESN’T have to be uninstalled manually. The setup process will delete it for you. Hope that this solves the confusion!