function objXMLHttp(){
	if (window.XMLHttpRequest){
		var objetoXMLHttp = new XMLHttpRequest();
		return objetoXMLHttp;
	}
	else if (window.ActiveXObject){//IE
		var versoes = [
					   "MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.5.0",
					   "MSXML2.XMLHttp.4.0","MSXML2.XMLHttp.3.0",
					   "MSXML2.XMLHttp.2.0","MSXML2.XMLHttp"
					   ]
		for(var i = 0; i < versoes.length; i++){
			try{
				var objetoXMLHttp = new ActiveXObject(versoes[i]);
				return objetoXMLHttp;
			}catch(ex){}
		}
	}
	return false;
}

function getDados(objForm){
	var params = new Array();
	for(var i=0; i < objForm.elements.length; i++){
		var parametro = encodeURIComponent(objForm.elements[i].name);
		parametro += "=";
		parametro += encodeURIComponent(objForm.elements[i].value);
		params.push(parametro);
	}
	return params.join("&");
}

function setDados(objForm){
	for(var i=0; i < objForm.elements.length - 3; i++){
		objForm.elements[i].value = "";
	}	
}

function enviar(formulario, pg, callback){
	var info = "";
	var dados = getDados(formulario);
	var oXMLHttp = objXMLHttp();
	oXMLHttp.open("POST",pg,true); 
	oXMLHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded; charset=utf-8");
	oXMLHttp.onreadystatechange = function(){
		if(oXMLHttp.readyState == 4){
			if(oXMLHttp.status == 200){
				info = oXMLHttp.responseText;
				callback(info);						
			}else{ 
				info = "Ocorreu o erro: "+ oXMLHttp.statusText;
				callback(info);						
			}
		} 	
	}
	oXMLHttp.send(dados);
}