potresti provare con qualcosa del genere
codice:
 
<SCRIPT LANGUAGE=javascript>
<!--
	var WinModulo
	function OpenModulo(strFinestra){
		var ScreenX = screen.availWidth 
		var ScreenY = screen.availHeight
		var x = parseInt(ScreenX - 10);
		var y = parseInt(ScreenY - 30);
		
		if (typeof(WinModulo)!= 'undefined'){
			WinModulo.close()
		}
		
					
		//WinModulo = window.open ('' , 'WinModulo','')
		WinModulo = window.open (strFinestra , 'WinModulo','left=0,top=0,directories=no,titlebar=no,resizable=yes,directories=no,status=no,toolbar=no,location=no,menubar=no,scrollbars=yes,width=' + x + ',height=' + y )
	}
	OpenModulo('peppe.htm')
//-->
</SCRIPT>