SQL Server 2005 is supported for new and upgrade installs of MOM 2005 SP1. The following hotfixes are publicly available for download and are required. Two (new binaries) require installation on Management Servers, the third (SQL table update) installation on the SystemCenterReporting database server (if one exists).
The following article covers the support statement for support of SQL Server 2005 by MOM 2005 Service Pack 1 and some caveats for support of x86, ia64 and x64 versions of SQL Server for hosting the OnePoint and SystemCenterReporting databases.
Please read the following articles which explain why each hotfix is required