Using SQL Server 2008 Express in Dynamics NAV 2009
NAV 2009 will install SQL Server Express 2005 by default if no SQL server is installed. So if you would like to use SQL Server Express 2008 instead, this is the way to go:
The Demo installation of NAV 2009 is looking for a SQL Server instance called MSSQLSERVER. If the installer can’t find this instance SQL Server Express 2005 will be installed and the Demo Database will be attached to SQL Server 2005 even though you might have had SQL Server Express 2008 installed.
So to install on SQL Server Express 2008 you need to set the instance name to MSSQLSERVER. This way NAV 2009 will install the Demo Database on SQL Server 2008.