function performAjaxQuery (ruta, params, target)
{
  var xmlHttp;
  
  try
  {
    // Firefox, Opera 8.0+, Safari
    xmlHttp = new XMLHttpRequest();
  }
  catch (e)
  {
    // Internet Explorer 6.0+
    try
    {
      xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e)
    {
      // Internet Explorer 5.5+
      try
      {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (e)
      {
        alert("Your browser does not support AJAX!");
        return false;
      }
    }
  }
  
  
  xmlHttp.onreadystatechange = function ()
  {
    if (xmlHttp.readyState == 4)
    {
      document.getElementById(target).innerHTML = xmlHttp.responseText;
    }
  }
   
  xmlHttp.open("POST", ruta, true);
  xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
  xmlHttp.send(params);

}