function xhrRequest() {
	
	var xhrSend = null;
	
	try {
  		// Firefox, Opera 8.0+, Safari
  		xhrSend = new XMLHttpRequest();
  	} catch (e) {
  		// Internet Explorer
  		try {
			xhrSend = new ActiveXObject("Msxml2.XMLHTTP");
    	} catch (e) {
			xhrSend = new ActiveXObject("Microsoft.XMLHTTP");
    	}
  	}

	return xhrSend;

}

function envia_request(url, formulario) {

	var xhrRec = xhrRequest();
	
	if (xhrRec == null) {
	  alert ("O seu browser não tem suporte a AJAX!");
	  return;
	}
	
	xhrRec.open('GET', url, true);
	
	xhrRec.onreadystatechange = function() {
		if (xhrRec.readyState == 4 && xhrRec.status == 200) {
			document.getElementById(formulario).innerHTML = xhrRec.responseText;
			xhrRec = null;
		}
	};
	
	xhrRec.send(null);	
}