function popaWindow(url) {
intro = window.open(url,'intro','width=660,height=520,resizable=0,scrollbars=0,toolbar=0,directories=0,status=0,');
var width = 660; 
var height = 520;
var aw = screen.availWidth; 
var ah = screen.availHeight; 
var xPos = (aw - width)/2; 
var yPos = (ah - height)/2; 
intro.moveTo(xPos,yPos);
	}