Unable to connect SQL Server 2005

When you try to connect to an instance of Microsoft SQL Server 2005 from a remote computer, you may receive an error message. This problem may occur when you use any program to connect to SQL Server.

This is because to connect to SQL Server Database Engine you must have a network protocol enabled. You can use SQL Server Configuration Manager to enable, disable, and configure network protocols.

Please refer to this site: http://msdn2.microsoft.com/en-us/library/ms187892.aspx on

How to configure SQL Server 2005 to allow remote connections.