function imageswap(name)
{
    var x = document.getElementById(name);
    var y = document.getElementById(name+'-on');

    var z = x.src;
    x.src = y.src;
    y.src = z;
}

function navon(name)
{
    document.images['nav-' + name].src='Images/nav-' + name + '-on.png';
}

function navoff(name)
{
    document.images['nav-' + name].src='Images/nav-' + name + '.png';
}