[vbmechanic]

At the top of global.php:

PHP Code:

if ( !preg_match("/^www.usethisdomain.com/i",$_SERVER[HTTP_HOST]) and !preg_match("/^usethisdomain.com/i",$_SERVER[HTTP_HOST]) ) {
    header("HTTP/1.1 301 Moved Permanently"); 
    if (strlen($_SERVER['QUERY_STRING'])>0)
        header("location:http://www.usethisdomain.com$PHP_SELF?$_SERVER[QUERY_STRING]");
    else
        header("location:http://www.usethisdomain.com$PHP_SELF");
    exit;
} 


This bit of code will forward the user and keep the current location and query string intact. It will also send search engines a proper forwarding code. Replace "usethisdomain.com" with the proper domain name that you'd like people to always use.