function openWindow(url, width, height) {
	
	if (width == undefined)  var width = 800;
	if (height == undefined) var height = 600;
	
	var wstat;
	var ns4up  = (document.layers) ? 1 : 0;
	var ie4up  = (document.all) ? 1 : 0;
	var xsize  = screen.width;
	var ysize  = screen.height;
	var xpos= (xsize - width)/2;
	var ypos= (ysize - height)/2;
	wstat = window.open(url,"PopUp","scrollbars=yes,status=no,toolbar=no,location=no,directories=no,resizable=yes,menubar=no,width="+width+",height="+height+",screenX="+xpos+",screenY="+ypos+",top="+ypos+",left="+xpos)
}