WebParts Err [Sql Server 2005 failure]

I have my app configured for windows authentication. Every thing seemed to work fine until I added webparts! I am getting following error when I try to run my page. I do not have SQL Server 2005 or SQL Express installed as I intend to use windows authentication for the intrante application. Can someone help me here please.

An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)