function ajax (url, campo, method , formulario) {
	
	if(method == null)
		method = "GET";

	var string = null;
	
	if(formulario != null)
		string = percorre(document.getElementById(formulario));

	var req = null;
	
	try {
		req = new XMLHttpRequest();
		}
	catch(erro1) {
		try {
			req = new ActiveXObject("Msxml2.XMLHTTP");
			}
		catch(erro2) {
			try {
				req = new ActiveXObject("Microsoft.XMLHTTP");
				}
			catch(erro3){
				req = false;
				}
			}
		}
	
	
	if (req) {
		document.getElementById(campo).innerHTML = '<img src="painel/img/carregando_azul.gif">&nbsp;&nbsp;<font size=1>Carregando...</font><br />';
		
		req.onreadystatechange = function() { 	try {
													if (req.readyState == 4)
														if (req.status == 200)
															document.getElementById(campo).innerHTML = req.responseText;
														else {
															alert("Houve um problema na conexão: " + req.statusText);
															document.getElementById(campo).innerHTML =	"";
															}
														
													}
													catch( e ) {
														alert('Houve um problema na requisição: ' + e.description);
														document.getElementById(campo).innerHTML =	"";
														}
												 };
		req.open( method, url, true);
		req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=iso-8859-1;");

		req.send(string);
		} 
	}