//Para armar el obj. AJAX (seguro ya lo tenes pero...)
function createAjax(){
	var obj = false;
	
	if(window.XMLHttpRequest){
		try {
			//Mozilla - Firefox, etc
			obj = new XMLHttpRequest();
		}
		catch (e){
			request = false;
		}		
	}else if (window.ActiveXObject){
		try{
			obj = new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e){
			try{
				obj = new ActiveXObject("Microsoft.XMLHTTP");				
			}
			catch (e){
				obj = false;
			}				
		}		
	}
	if (obj)	{
		return obj;
	}else{
		return null;
	}
}