MOM 2005 SP1 is not compatible with SQL Server 2005 without these 3 hotfixes.
Unable to discover computers in AD after upgrading to .NET Framework 2.0
Errors can occur when data collected by MOM 2005 SP1 is queried with SQL Server 2005 Reporting Services
Deadlocks may occur with MOM 2005 SP1 on SQL 2005