December issue of SQL Server Magazine had an article written by Michelle Poolet on data modeling software. You have to be a subscriber to access the website and the article though. The vendors she had reviewed were:1. Quest Software's Toad Data Modeler for SQL Server 3.5, Xpert Edition2. Altova's DatabaseSpy 2011, Enterprise Edition3. Datanamic Solutions' DeZign for Databases 6.2, Expert Edition4. Embarcadero Technologies' ER/Studio Enterprise 8.55. CA's ERwin Data Modeler (DM) 7.36. Sybase's PowerDesigner Studio Enterprise 15.2
If you are a subscriber by any chance, the InstantDoc ID is #128921. I only flipped through the article, but from what I recall, none of them were free. You could look up the vendor sites to see if they have free versions.