browser_name = navigator.appName;
browser_version = parseFloat(navigator.appVersion); 
if (browser_name == "Netscape" && browser_version >= 3.0) { 
    roll = 'true';
} else if (browser_name == "Microsoft Internet Explorer" && browser_version >= 4.0) {
    roll = 'true';
} else {
    roll = 'false';
}

if (roll == 'true') {
    var imglist = new Array (
        "/images/menu/brand_on.gif",
        "/images/menu/products_on.gif",
        "/images/menu/contacts_on.gif"
    );
    var imgs = new Array();
    var count;
    if (document.images)
    for (count = 0; count < imglist.length; count++) {
        imgs[count]     = new Image();
        imgs[count].src = imglist[count];
    }
}

function over(img, ref)
{
    if (roll == 'true') {
        document.images[img].src = ref;
    }
}

function out(img, ref)
{
    if (roll == 'true') {
        document.images[img].src = ref;
    }
}