SQL Server Enterprise Manager includes a diagramming tool. It isn't as good as ERwin or other full-featured ERD tools, but it is included. In SQL Server 2000, expand the Enterprise Manager tree to display the contents of the database. Right-click the Diagrams folder and select New Database Diagram from the pop-up menu to display the Create Databse Diagram Wizard's Welcome dialog box. Click the Next button to display a dialog box to select tables to add to the diagram. Click the Add related tables automatically check box. That should get you started.