It seems that the guys in the SQL Server team working hard … Cumulative Update 1 (CU1) for SQL Server 2008 Service Pack 1 (SP1) contains only hotfixes that were released in Cumulative Update 4 for SQL Server 2008. Moreover, you will have to install SP1 before applying CU1 (for SP1). This build of the cumulative update package is also known as build 10.00.2710 You can find more information here: http://support.microsoft.com/kb/969099/ Enjoy!