function open_window(aPage,aWidth,aHeight) {		
	if (!aWidth)
		aWidth = 480;
	if (!aHeight)
		height = 350; 
		
	lLeft = screen.width / 2 - aWidth / 2;
	lTop = screen.height / 2 - aHeight / 2;
		
	OpenWin = window.open(aPage, "window", "toolbar=no,menubar=no,location=no,scrollbars=yes,resizable=yes,width=" + aWidth + ",height=" + aHeight + ",left=" + lLeft + ",top=" + lTop + "");
}