function popupWindow(url, title, w, h) 
{
	leftPosition = (screen.availWidth) ? (screen.availWidth-w)/2 : 0;
	topPosition = (screen.availHeight) ? (screen.availHeight-h)/2 : 0;
	settings = 'height='+h+',width='+w+',top='+topPosition+',left='+leftPosition+',menubar=0,scrollbars=0,resizable=0,status=0,titlebar=0,toolbar=0';
	win = window.open(url, title, settings);
	if (parseInt(navigator.appVersion) >= 4) { 
		win.window.focus(); 
	}
}