When you try to Reverse Engineer SQL 2005 DB from Visio 2003. You may get this error “The currently selected Visio driver is not compatible with the data source."
I think SQL Server 2005 compatible driver will be shiped later.
However, you may use Generic OLE DB Provider, and then select Microsoft
OLE DB Provider for ODBC drivers, it can successfully interpret tables with
from SQL Server 2005.