Each SQL server instance by default is set up to use port 1433 for SQL communication thought the network. You can download the SQL Management Studio Express from Microsoft and go into the properties of your SQL express instance to make sure that the necessary configuration settings are in place. When connecting to the SQL Express or SQL 2005 servers, be sure to specify the proper SQL instance. Example: ServerName\SQLExpress or ServerName\SQL2005.

 Microsoft SQL Management Studio Express download page:

http://www.microsoft.com/downloads/details.aspx?FamilyID=C243A5AE-4BD1-4E3D-94B8-5A0F62BF7796&displaylang=en

Thank you,