I ran across a challenge running SQL 2000 side-by-side with SQL 2005. 

Scenario

• Need to run SQL 2005 Management Studio (with ability to migrate DTS packages into 2005)
• Need to run SQL 2000 Enterprise Manager (need to manage SQL 2000 installs including diagrams)

Symptoms

With SQL 2005 Mgmt Studio installed with SQL 2000 client tools you may receive an error when running SQL 2000 EM like...

Entry Point Not Found
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The procedure entry point ?ProcessExecute@@YAXPAUHWND__@@PBG1@Z could not be located in the dynamic link library SEMSFC.dll.

SQL Server Enterprise Manager
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Connection to application object failed. Ensure that no program modules have been deleted.

Resolution

• Install SQL 2000 Client Tools (including SP4)
• Install SQL 2005 Management Studio (ensure that compatibility files are installed)
• Install SQL 2000 DTS Designer Components from SQL 2005 Management Studio Feature pack found at http://www.microsoft.com/downloads/details.aspx?familyid=D09C1D60-A13C-4479-9B91-9E8B9D835CDC&displaylang=en
• At this point you should be able to manage both SQL 2000 and 2005 server from the Management Studio, however the SQL 2000 EM will give you an errors listed in symptoms
• Install SQL Server 2000 SP4