if (window.XMLHttpRequest){

          // If IE7, Mozilla, Safari, etc
          var xmlHttp = new XMLHttpRequest()

}
else 
{
if (window.ActiveXObject){

          // ...otherwise, use the ActiveX control for IE5.x and IE6
          var xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
          }

}

function getInfo()
{
	xmlHttp.open('post','dropdown.php?brandid='+ document.ins_mm.brandid.selectedIndex);
	xmlHttp.onreadystatechange = handleInfo;
	xmlHttp.send(null);
}

function handleInfo()
{
	if(xmlHttp.readyState == 1)
	{
		document.getElementById('main').innerHTML = 'loading ..';
	}

	else if(xmlHttp.readyState == 4)
	{
		var response = xmlHttp.responseText;
		document.getElementById('main').innerHTML = response;
	}
}