About Mssql Server connection

[black_hawk]

Hi friends,
As title refers, my problem is related with connection to the sql server. I use MSSQL Express 2005. My program, that is written in php, tries to connect to the server but the connection is failure.I didn't create an account from login under root and my connection type is Windows authentication.I tried to login with various combinations like below:

//1
mssql_connect("localhost","blackhawk","111");

//2
mssql_connect("SQLEXPRESS","blackhawk","111");

//3
mssql_connect("127.0.0.1","blackhawk","111");

//4
mssql_connect("SQLEXPRESS","sa","sa");

//5
mssql_connect("localhost","root","111");

But the connection is not realized. Is there anyone to help me about this?

Server name :BLACKHAWK/SQLEXPRESS
Connection :BLACKHAWK/Blackhawk