function ventanaPopup(anch, w, h)
{

	var l = 0;
	var t = 0;
	try {
		l = (screen.width - w) >> 1;
		t = (screen.height - h) >> 1;
	} catch(E) {}

	var w = window.open(anch.getAttribute("href"), "_blank",
		"toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=1,resizable=1,width="+w+",height="+h
		+(l+t ? ",left="+l+",top="+t : ""));

	return false;
}