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

function stateChanged() 
{ 
	if (xmlHttp.readyState==4)
	{ 
		document.getElementById("content").innerHTML=xmlHttp.responseText;
	}
}

function changeContent( url )
{
	xmlHttp=GetXmlHttpObject();
	if (xmlHttp==null)
    {
	  alert ("Your browser does not support AJAX!");
	  return;
	} 
	var url="ajax/content.php";
	xmlHttp.onreadystatechange=stateChanged;
	xmlHttp.open("GET",url,true);
	xmlHttp.send(null);
}