The problem seems to be the following:
I start SQL Server Enterprise Manager and change the authentification method (on the security tab) to "SQL Server and Windows", but when i reopen the security properties of my server it has been reset to "Windows Only".
(I'm using "Microsoft OLE DB Provider for SQL Server")
i guess his question is "what is trusted connection". it means that sql server does not perform any authentication itself other than validating that the windows login is granted permission to login. contrary to standard sql server security, no password validation occurs.