function popup(w,h,site) {
	x = screen.availWidth/2-w/2;
	y = screen.availHeight/2-h/2;
	var popupWindow = window.open('','','width='+w+',height='+h+',left='+x+',top='+y+',screenX='+x+',screenY='+y);
	popupWindow.document.write(site);
}