var xmlHttp

function GetXmlHttpObject()
{ 
	var objXMLHttp=null
	if (window.XMLHttpRequest)
	{
		objXMLHttp=new XMLHttpRequest()
	}
	else if (window.ActiveXObject)
	{
		objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
	}
	return objXMLHttp
}

function stateChanged()
{ 
	if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
	{ 
	   //document.getElementById("txtCidades").innerHTML=xmlHttp.responseText 
	   var spanElement = document.getElementById('txtCidades');
           spanElement.innerHTML = '';

           try {
             spanElement.innerHTML = xmlHttp.responseText;
           }

           catch (e) {
             // IE fails unless we wrap the string in another element.
             var wrappingElement = document.createElement('div');
             wrappingElement.innerHTML = xmlHttp.responseText;
             spanElement.appendChild(wrappingElement);
           }        
	} 
} 

function BuscarCidade(estado,cidade)
{ 

	xmlHttp=GetXmlHttpObject()
	if (xmlHttp==null)
	{
		alert ("Browser does not support HTTP Request")
		return
	} 
	var url="/cidades.php"

	url=url+"?q="+estado
	if (cidade!='')
	{
		url=url+"&p="+cidade	
	}
	url=url+"&sid="+Math.random()

	xmlHttp.onreadystatechange=stateChanged
	xmlHttp.open("GET",url,true)
	xmlHttp.send(null)
}