function OpenCenteredWindow( url, width, height )
{
       var left = Math.floor( (screen.width - width) / 2);
	   var top = Math.floor( (screen.height - height) / 2);
	   var winParms = "top=" + top + ",left=" + left + ",height=" + height + ",width=" + width;
	   winParms += ",toolbar=no,status=no,scrollbars=yes,menubar=no,resizable=no,location=no,directories=no";
	   var win = window.open(url, '', winParms);
	   if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
	   return win; 	
}