var xmlHttp;
var act="";
var is_ie = (navigator.userAgent.indexOf('MSIE') >= 0) ? 1 : 0; 
var is_ie5 = (navigator.appVersion.indexOf("MSIE 5.5")!=-1) ? 1 : 0; 
var is_opera = ((navigator.userAgent.indexOf("Opera 6")!=-1)||(navigator.userAgent.indexOf("Opera/6")!=-1)) ? 1 : 0; 
var is_netscape = (navigator.userAgent.indexOf('Netscape') >= 0) ? 1 : 0;
function fetch_remote_page(AJAXURL, action)
{ 
		act=action;
		xmlHttp = GetXmlHttpObject(stateChangeHandler);
		xmlHttp_Get(xmlHttp, AJAXURL);	

}

function stateChangeHandler()
{
	if (xmlHttp.readyState == 4 || xmlHttp.readyState == 'complete')
	{
		var str = xmlHttp.responseText;
	//	alert(str)
		switch(act){
			case "CAPTCHA":
				var chk=str.split("_");
				document.getElementById("usr_avail").src='security_images/'+chk[0]+".jpg";
				document.getElementById("sessionid").value=chk[1];
			break;
			case "REFERRER":
				fetch_remote_page("http://www.siliconinfo.net/ajax_contact.php","CAPTCHA");
			break
		}
	}
}

function xmlHttp_Get(xmlhttp, url)
{
	if(act!="CAPTCHA"){
		xmlhttp.open("POST", url, true);
		var poststr="referrer="+escape(document.referrer);
		xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
	    xmlHttp.setRequestHeader("Content-Length",poststr.length);	
		xmlhttp.send(poststr);	
	}else{
		xmlhttp.open("GET", url, true);
		xmlhttp.send(null);
	}

}

function GetXmlHttpObject(handler)
{
	var objXmlHttp = null;
	if (is_ie)
	{
		var strObjName = (is_ie5) ? 'Microsoft.XMLHTTP' : 'Msxml2.XMLHTTP';
		try
		{
			objXmlHttp = new ActiveXObject(strObjName);
			objXmlHttp.onreadystatechange = handler;
		}
		catch(e)
		{
			alert('IE detected, but object could not be created. Verify that active scripting and activeX controls are enabled');
			return;
		}
	}
	else if (is_opera)
	{
		alert('Opera detected. The page may not behave as expected.');
		return;
	}
	else
	{
		objXmlHttp = new XMLHttpRequest();
		objXmlHttp.onload = handler;
		objXmlHttp.onerror = handler;
	}
	return objXmlHttp;
}