browser = navigator.appName;
ie = "Microsoft Internet Explorer";
netscape = "Netscape";

//Simple function to turn on an image
function onLink(navInput) {
    if (browser == netscape) {
        document['navHead'].document[navInput].src = 'images/' + navInput + '_on.gif';
    }
    else if (browser == ie) {
        document.all[navInput].src = 'images/' + navInput + '_on.gif';
    }
}

//Simple function to turn off an image
function offLink(navInput) {
    if (browser == netscape) {
        document['navHead'].document[navInput].src = 'images/' + navInput + '_off.gif';
    }
    else if (browser == ie) {
        document.all[navInput].src = 'images/' + navInput + '_off.gif';
    }
}