function redirect_if_not_supported() {
    var url = window.location.toString();
    var i = url.lastIndexOf('/');
    var agent = navigator.userAgent || '';
    var j = agent.indexOf('MSIE');
    if(j > 0) {
        var version = parseFloat(agent.substring(j + 5));
        if(version > 0  &&  version < '6.0') {
            if(i > 0) {
                url = url.substring(0, i) + '/unsupported.html';
            }
            window.location= url;
        }
    }
}

redirect_if_not_supported();