If your web connector is correctly set up, then i believe that your code 
should work, if not try this method.

<?php
	$link = mssql_connect( "192.168.0.5","sa","" ) or die( "Couldn't 
connect to computer.<br>" );  
  	mssql_select_db( "db",$link );

	$query = "INSERT INTO hrmdetails VALUES
(NULL,'$forename','$surname');

$result = mssql_query($query);
?>