function BrowserVersion() {
    var browser = window.navigator.appName;
    var appVer = window.navigator.appVersion;
    var appVersion = 0;

    
    pos = appVer.indexOf("MSIE ");
    if (pos != -1) {
        pos2 = appVer.indexOf(";", pos + 1);
        appVersion = parseFloat(appVer.substring(pos + 5, pos2) - 0);
    }


   return appVersion;
}

function replaceImg(obj){
var ver=BrowserVersion();
if (ver==0) return;
if (ver <7  ){
var newpath = obj.outerHTML;
newpath = newpath.replace(".png",".gif");
obj.outerHTML = newpath;
}
}