First I would sugges to migrate the vCenter database to SQL 2008 standard and then proceed with the upgrade
Check Migrating the vCenter Server database from SQL Express 2005 to SQL Server 2008 to know how to move the database
First I would sugges to migrate the vCenter database to SQL 2008 standard and then proceed with the upgrade
Check Migrating the vCenter Server database from SQL Express 2005 to SQL Server 2008 to know how to move the database