function showWindow(url) {
	leftPos = 0
	topPos = 0
	height = 480

	if (screen) {
		leftPos = (screen.width-640)/2
		topPos  = (screen.height-480)/2
	}
	window.open(url, "", "toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=640,height=480,left="+leftPos+",top="+topPos);
}