browser = (((navigator.appName == "Netscape") && (parseInt(navigator.appVersion) >= 3 )) || ((navigator.appName == "Microsoft Internet Explorer") && (parseInt(navigator.appVersion) >= 4 )))

if (browser) {

        normal = new MakeArray(3)
        over   = new MakeArray(3)

        normal[1].src = "images/home.gif"
        normal[2].src = "images/tariffs.gif"
        normal[3].src = "images/map.gif"
        
        over[1].src = "images/home-over.gif"
        over[2].src = "images/tariffs-over.gif"
        over[3].src = "images/map-over.gif"
}

function MakeArray(n) {
        this.length = n
        for (var i = 1; i<=n; i++) {
                this[i] = new Image()
        }
        return this
}

function msover(num) {

        if ( browser) { 
                loadImage = "Image" + num;
                document.images[loadImage].src = over[num].src
        }
}

function msout(num) {

        if ( browser) {
                loadImage = "Image" + num;
                document.images[loadImage].src = normal[num].src
        }                  
}