Can''t install sp2 to Express?

Today, I attempted to install sp2 to my SQL 2005 Express instance and the install dialog would not allow me to check the box next to database services. At the bottom of the dialog it says this edition of SQL Server does not qualify for the update. It allowed other parts of the product to be updated, just not the engine.

This is on a Windows XP, SP2 box.

Shouldn't I be allowed to install the update for the database engine?

Thanks,

Del

Are you sure you've downloaded the SP meant for SQL Express? I got mine here:

http://www.microsoft.com/downloads/details.aspx?FamilyId=31711d5d-725c-4afa-9d65-e4465cdff1e7&displaylang=en#Requirements
|||Thanks, Mark. In the past the sp's pretty much applied to all editions. In this case, I did not realize there was a separate download.

Del