function objXmlHttp() {
	var xmlHttp;
	try { // Firefox, Opera 8.0+, Safari
		xmlHttp = new XMLHttpRequest();
	} catch (e) { // Internet Explorer
		try {
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e){
			try {
				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e)	{
				alert("Your browser does not support AJAX!");
				return false;
			}
		}
	}
	return xmlHttp;
}

function requestShipping(queryString){
	var xmlHttp = objXmlHttp();
	xmlHttp.onreadystatechange = function(){
		if(xmlHttp.readyState==4){
			document.getElementById('jshipping_box').innerHTML = xmlHttp.responseText;
			document.getElementById('jshipping_box').style.width = '98%';
			new Effect.Appear('jshipping_box', { duration: 0.4, from: .2, to: 1 });
		}else if(xmlHttp.readyState==1){
			document.getElementById('jshipping_box').getElementsByTagName('legend')[0].innerHTML = '* Loading *';
			new Effect.Appear('jshipping_box', { duration: 0.4, from: 1, to: .2 });
		}
	}
	
	xmlHttp.open("POST","shipping_response.php",true);
	xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	xmlHttp.send(queryString);
	return false;
}