function vIE(){return (navigator.appName=='Microsoft Internet Explorer')?parseFloat((new RegExp("MSIE ([0-9]{1,}[.0-9]{0,})")).exec(navigator.userAgent)[1]):-1;}
function knowBrowser(){
    var explorer = vIE();
    if(explorer >= 0 && explorer <= 6){
        document.getElementById('explorador').style.display = 'block';
        return;
    }
    document.getElementById('intro').style.display = 'block';
}
if(window.addEventListener) window.addEventListener('load', knowBrowser, false);
else window.attachEvent('onload', knowBrowser);