function executeXhr(callback, url) 
{   
   // branch for native XMLHttpRequest object   
   if (window.XMLHttpRequest) {   
     req = new XMLHttpRequest();   
     req.onreadystatechange = callback;   
     req.open("GET", url, true);   
     req.send(null);   
   } // branch for IE/Windows ActiveX version   
   else if (window.ActiveXObject) {   
     req = new ActiveXObject("Microsoft.XMLHTTP");   
     if (req) {   
       req.onreadystatechange = callback;   
       req.open("GET", url, true);   
       req.send();   
     }   
   }
}


function processAjaxResponse_checkEmail() 
{   
	// only if req shows "loaded"   
	if (req.readyState == 4) 
	{   
		// only if "OK"   
		if (req.status == 200) 
		{   
			document.getElementById("checkEmail").innerHTML = req.responseText;   
		} 
		else 
		{
			window.alert("There was a problem retrieving the XML data: " +  req.statusText);   
		}   
   	}   
}

function processAjaxResponse_checkName() 
{   
	// only if req shows "loaded"   
	if (req.readyState == 4) 
	{   
		// only if "OK"   
		if (req.status == 200) 
		{   
			document.getElementById("checkName").innerHTML = req.responseText;   
		} 
		else 
		{
			window.alert("There was a problem retrieving the XML data: " +  req.statusText);   
		}   
   	}
}