MSSQL Authentication Modes

[Anon]

I'm new to both PHP and SQL Server. I've got a 2k box with SQL 2000 and IIS. I'm trying to conncect to a DB with this code.

$hostname = "localhost";
$username = "username";
$password = "password";
$dbName = "DB";
$Table = "table";

mssql_connect($hostname,$username,$password) or DIE("DATABASE FAILED TO RESPOND.");

mssql_select_db($dbName) or DIE("Table unavailable");

$query = "bla bla bla";

MSSQL_QUERY($query);

The Problem is I can't connect with a user that is set with Windows Authentication (i.e. windwos user). If i set a user up with SQL Authentication (i.e. standard user) it works fine. The message i get is as follows:

Warning: MS SQL message: Login failed for user 'username'. (severity 14)

Any Help would be great.

Thanks,
Kyle