if (document.images) {
    preload_image_object = new Image();
    // set image url
    image_url = new Array();
    image_url[0] = "http://www.internetsolutionsireland.com/images/home_on.png";
    image_url[1] = "http://www.internetsolutionsireland.com/about_us_on.png";
    image_url[2] = "http://www.internetsolutionsireland.com/images/services_on.png";
    image_url[3] = "http://www.internetsolutionsireland.com/images/portfolio_on.png";
    image_url[4] = "http://www.internetsolutionsireland.com/images/quotation_on.png";
    image_url[5] = "http://www.internetsolutionsireland.com/images/contact_us_on.png";

    var i = 0;
    for (i = 0; i <= 6; i++)
        preload_image_object.src = image_url[i];
}