function verificaAjax()
  {
var url;
  try
    {
    // Firefox, Opera 8.0+, Safari
    url=new XMLHttpRequest();
    }
  catch (e)
    {
    // Internet Explorer
    try
      {
      url=new ActiveXObject("Msxml2.XMLHTTP");
      }
    catch (e)
      {
      try
        {
        url=new ActiveXObject("Microsoft.XMLHTTP");
        }
      catch (e)
        {
        alert("Seu browser nao possui suporte para AJAX!");
        return false;
        }
      }
    }
	return url;
  }

function abrir(acao){
	var xmlHttp=verificaAjax();
	
	xmlHttp.onreadystatechange=function()
	{
		if(xmlHttp.readyState==4)
		{
			document.getElementById("conteudo").innerHTML=xmlHttp.responseText;	
		}
	}
	xmlHttp.open("POST",acao,true);
	xmlHttp.send(null);
}


function enviaForm(idForm, acao){
    // Captura o form
    f = document.getElementById(idForm);
    // inicializa nova URL
    var query="";
    //Percorre elementos do formulario
    for (i=0;i<f.elements.length;i++){
        // concatena a variavel na query
        query += f.elements[i].name + '=' + escape(encodeURI(f.elements[i].value));
    }
    // envia o formulario
    enviaPostRequest(acao, query);
}


function enviaPostRequest(url, parameters) {
      http_request = verificaAjax();
      
      http_request.onreadystatechange=function()
	{
		if(xmlHttp.readyState==4)
		{
			document.getElementById("conteudo").innerHTML=http_request.responseText;	
		}
	}

      http_request.open('POST', url, true);
      http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      http_request.setRequestHeader("Content-length", parameters.length);
      http_request.setRequestHeader("Connection", "close");
      http_request.send(parameters);
   }