connecting to a sql server database with nt authentication

I am trying to connect to a sql server database through pear, using nt authentication. I have the following set up as my dsn: phptype = mssql dbsyntax = false username = domainname\username password = password protocol = false hostspec = servername,1433 port = false socket = false database = databasename obviously I've changed username, password, etc to general identifiers, but it is in this format - I think that the problem is that I've not formatted the username correctly, but I've tried all sorts with this with no success: \\domainname\username <file:///\\domainname\username> //domainname/username username domainname\username domainname/username help!