var new_Prod;

function showMainProd(){
new_Prod=GetXmlHttpObject()
if (new_Prod==null)
 {
 alert ("Su navegador no soporta AJAX");
 return
 }
var url="get_main_cont.php"
url=url+"?sid="+Math.random();
new_Prod.onreadystatechange=MainCont;
new_Prod.open("GET",url,true);
new_Prod.send(null);

}

function MainCont() 
{ 
if (new_Prod.readyState==4 || new_Prod.readyState=="complete")
 { 
 document.getElementById("main_cont").innerHTML=new_Prod.responseText; 
 } 
}

function GetXmlHttpObject()
{
var new_Prod=null;
try
 {
 // Firefox, Opera 8.0+, Safari
 new_Prod=new XMLHttpRequest();
 }
catch (e)
 {
 //Internet Explorer
 try
  {
  new_Prod=new ActiveXObject("Msxml2.XMLHTTP");
  }
 catch (e)
  {
  new_Prod=new ActiveXObject("Microsoft.XMLHTTP");
  }
 }
return new_Prod;
}