Centralizando pop-ups ao carregar html - Javascript

script language="javascript"
< >
var win = null;
function NovaJanela(pagina,nome,w,h,scroll){
LeftPosition = (screen.width) ? (screen.width-w)/2 : 0;
TopPosition = (screen.height) ? (screen.height-h)/2 : 0;
settings = 'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',resizable'
win = window.open(pagina,nome,settings);
}
/script
< >
/head
< >
body bgcolor="#000000"
<
onLoad="NovaJanela('contato.html','nomeJanela','450','450','yes');return false"
>