When you use DMO to connect to a Sql Server 2005 instance, you will likely get the following error:

Microsoft SQL-DMO (ODBC SQLState: 42000) error ‘800ad903’
[Microsoft][ODBC SQL Server Driver][SQL Server]To connect to this server you must use SQL Server Management Studio or SQL Server Management Objects (SMO).

This is because in Sql Server 2005, DMO has been deprecated. In its place is a new thing called SMO.

Microsoft does provide a backward compatibility component for customers using DMO to connect to Sql Server 2005. However, you will need to move to SMO sooner or later, because there will come a day when DMO will not be supported at all. To get the DMO backward compatibility component, go to Sql Server 2005 Feature Pack page, and download SQLServer2005_BC installation package.

Sometimes you will need to manually register sqldmo.dll in C:\Program Files\Microsoft SQL Server\80\Tools\Binn\sqldmo.dll using regsvr32. For example, if you get the Server.CreateObject Failed message, you will need to register that dll manually. In asp web page application, you will get the message below:

Server object error ‘ASP 0177 : 8002801d’
Server.CreateObject Failed