var clientPC = navigator.userAgent.toLowerCase();
var clientVer = parseInt(navigator.appVersion);

var bz_is_ie = ((clientPC.indexOf("msie") != -1) && (clientPC.indexOf("opera") == -1));
var bz_is_ff = ((clientPC.indexOf('mozilla')!=-1) && (clientPC.indexOf('spoofer')==-1)
                && (clientPC.indexOf('compatible') == -1) && (clientPC.indexOf('opera')==-1)
                && (clientPC.indexOf('webtv')==-1) && (clientPC.indexOf('hotjava')==-1));

var os_is_win = ((clientPC.indexOf("win")!=-1) || (clientPC.indexOf("16bit") != -1));
var os_is_mac = (clientPC.indexOf("mac")!=-1);

var bz_is_ie6 = false
var strChUserAgent = navigator.userAgent;
var intSplitStart = strChUserAgent.indexOf("(",0);
var intSplitEnd = strChUserAgent.indexOf(")",0);
var strChMid = strChUserAgent.substring(intSplitStart, intSplitEnd);

if(strChMid.indexOf("MSIE 6") != -1) bz_is_ie6 = true;