var isNS4 = (document.layers);
var isIE = (document.all);
var isIE7 = (isIE && navigator.userAgent.indexOf("MSIE 7")>-1);
var isOP = (document.all && navigator.userAgent.toUpperCase().indexOf("OPERA")>-1);
var isNS_MZ = (document.getElementById && !document.all);
if (isOP) isIE = false;