ADO Connection To MSSQL Server 2005... Need Help

Hi,

at first a few things about my system:
I use Visual Studio 2005 Pro on WinXP SP2 and I have recently installed MSSQL Server 2005 Express on my system.

I want to establish a connection to the MSSQL Server from C++ (not .NET) using ADO.

For this I use the following connection String:

Open(L"Provider=SQLNCLI;Server=FREECASTLE;Integrated
Security=SSPI;DataTypeCompatibility=80;MARS
Connection=True;",L"",L"",ADODB::adConnectUnspecified);



This works. But this is not exactly that what I wanted, because here
just my Windows Authentication is used. I want to be able to pass
username and password for users that are allowed to access the SQL
Server. Here my first confusion begins: I have the option to pass the username and password into the connection string (User Id and Password) or I guess that I can pass them also as parameter 2 and parameter 3. But with trying both of these options I get always a connection error that my specified Username is not be trusted ( I don't know how the message looks in the English version, because I have the german version), but I suppose you know what I mean.

Of course I have to create such accounts in the SQL Server before trying to login with them. I guess that I made something wrong when doing this. I started the Server Manager Studio and there I navigated into the Object Explorer. In the folder Security I created a new account for testing (using SQL Server Authentication). But I cannot use that account for logging in.

I have to admit that I am very new to the SQL Server thing, so I hope someone can help me or can give me hints on what to do better. I am very thankful for every reply...