if(document.images)
{
    var image_array = new Array();
    // enumeration of the "active" images
    image_array[0] = "/img/nav/button2.gif";
    image_array[1] = "/img/nav/books2.gif";
    image_array[2] = "/img/nav/about2.gif";
    image_array[3] = "/img/nav/contact2.gif";
    image_array[4] = "/img/nav/comingsoon2.gif";

    var preload_image = new Array ();
    for(var i=0; i<image_array.length; i++)
    {
        preload_image[i]= new Image();
        preload_image[i].src = image_array[i];
    }
}

function roll(name,source)
{
    name.src = source;
}
function rollout(name,ori)
{
    name.src = ori;
}