here is the script that i been working on , it is supposed to integrate user and pass when opened
Change your code to this
window.open('https://secure.brosix.com/webclient/? nid=4510&user=$name&pass=$pass&hideparams=1', 'width=710,height=555,left=160,top=170')";
echo $link;
?>
Additional Note
You should consider using fancybox which can load webpages as a whole in a popup window using iframes. There are other options as well feel free to explore!