function xmlhttpPost(strURL) {
    var xmlHttpReq = false;
    var self = this;

    // Create our object (multiple browsers).
    if (window.XMLHttpRequest) { // Mozilla/Safari
        self.xmlHttpReq = new XMLHttpRequest();
    }
    else if (window.ActiveXObject) { // Internet Explorer
        self.xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
    }

    // Set the url.
    self.xmlHttpReq.open('POST', strURL, true);

    // Set our request header.
    self.xmlHttpReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');

    // Link a function to the event 'onreadystatechange'.
    self.xmlHttpReq.onreadystatechange = function() {
        if (self.xmlHttpReq.readyState == 4) {
            document.getElementById("product_overview").innerHTML = self.xmlHttpReq.responseText;
        }
    }

    // Send our request.
    self.xmlHttpReq.send(getquerystring());
}

function getquerystring() {
    var qstr = "";

        form = document.getElementById("overzicht_form").elements;
        for(i=0; i<form.length; i++)
        {
    	    qstr = qstr + form[i].name + '=' + escape(form[i].value) + '&';
        }

/*
    if (document.getElementById("overzicht_div").childNodes.length > 0)
    {

        var form = document.getElementById("overzicht_div").childNodes;
        for (var x in form)
        {
    	    if (form[x] && form[x].value && form[x].name)
    	    {
    	        qstr = qstr + form[x].name + '=' + escape(form[x].value) + '&';
    	    }
        }

    } else {

        form = document.getElementById("overzicht_form").elements;
        for(i=0; i<form.length; i++)
        {
    	    qstr = qstr + form[i].name + '=' + escape(form[i].value) + '&';
        }

    }*/

    return qstr;
}