function GetXmlHttpObject()
{
	if (window.ActiveXObject)
  	{
  		// code for IE6, IE5
  		return new ActiveXObject('Microsoft.XMLHTTP');
 	}

	if (window.XMLHttpRequest)
  	{
  		//return new ActiveXObject('Msxml2.XMLHTTP');
  		return new XMLHttpRequest();
	}
	return null;
}

function ajax(url,param,id)
{
	var el=document.getElementById(id);
	var opl;
	var oh;
	var obp;
	var ob;

	var xmlhttp=GetXmlHttpObject();
	if (xmlhttp==null)
	{
	    alert ('Your browser does not support AJAX!');
		return;
	}
   // alert(url+'?'+param+'&time='+(new Date()).getTime());
	xmlhttp.open('GET',url+'?'+param+'&time='+(new Date()).getTime(),true);
	xmlhttp.onreadystatechange=function()
	{
 		if(xmlhttp.readyState==1)
 		{
			el.innerHTML = "";

   			//modificamos el estilo de la div, mostrando una imagen de fondo
   			ob=el.style.background;
   			opl=el.style.paddingLeft;
   			obp=el.style.backgroundPosition;
   			oh=el.style.height;

            el.style.background = "url('common/img/casa_rot.gif') no-repeat";
            el.style.paddingLeft="150px";
            el.style.height = "200px";
            el.style.backgroundPosition="center center";

         }
         else if(xmlhttp.readyState==4)
         {
         	if(xmlhttp.status==200)
         	{
          		//mostramos los datos dentro de la div

                //el.innerHTML = "Cargado.";
                //el.style.background = "url('loader.gif') no-repeat";
	            el.style.background = ob;
	            el.style.paddingLeft=opl;
	            el.style.height = oh;
	            el.style.backgroundPosition=obp;
	            //el.style.width="720px";
                el.innerHTML = xmlhttp.responseText;

            }
            else if(xmlhttp.status==404)
            {
                el.innerHTML = "La página no existe";
            }
            else
            {
          		//mostramos el posible error
          		el.innerHTML = "Error:".xmlhttp.status;
            }
          }

        }
		xmlhttp.send(null);
	}