Autori: unknown, modified and explained from www.webmasterpaolo.com
Se invece volete posizionare la finestra non proprio centrale modificate i parametri da window.moveTo(0,0) a window.moveTo(300,200)
Lo script da inserire in html
<script language="Javascript">
<!--
// ***********************************************
// AUTHOR: WWW.CGISCRIPT.NET, LLC
// URL: http://www.cgiscript.net
// Modificato da Webmasterpaolo.com
// ***********************************************
window.moveTo(0,0)
window.resizeTo(screen.width,screen.height)
//-->
</script>