Use isto:
<!- Oculte este script de brownsers antigos
if ((parseInt(navigator.appVersion) > 3) && (navigator.appName == "Netscape")) {
var the_window = window.open('http://link.com.br/,...t=200,width=200');
var screen_height = window.screen.availHeight;
var screen_width = window.screen.availWidth;
var left_point = parseInt(screen_width / 2) - 100;
var top_point = parseInt(screen_height / 2) - 100;
the_window.moveTo(left_point,top_point);
}
-> Fim do ocultamento
