is it IE6 or IE7

This is the Javascript code for checking whether the browser is IE6, or IE7....
var isIE = document.all ? true : false;
IE4 = ((document.all) && (navigator.appVersion.indexOf("MSIE 4.") != -1)) ? true : false;
IE5 = ((document.all) && (navigator.appVersion.indexOf("MSIE 5.") != -1)) ? true : false;
IE6 = ((document.all) && (navigator.appVersion.indexOf("MSIE 6.") != -1)) ? true : false;
IE7 = ((document.all) && (navigator.appVersion.indexOf("MSIE 7.") != -1)) ? true : false;