function newImage(arg) {
    if (document.images) {
        rslt = new Image();
        rslt.src = arg;
        return rslt;
    }
}

function changeImages() {
    if (document.images && (preloadFlag == true)) {
        for (var i=0; i<changeImages.arguments.length; i+=2) {
            document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
        }
    }
}

var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        home_over = newImage("images/home_.jpg");
        about_over = newImage("images/about_.jpg");
        news_over = newImage("images/news_.jpg");
        portfolio_over = newImage("images/portfolio_.jpg");
        services_over = newImage("images/services_.jpg");
        contact_over = newImage("images/contact_.jpg");
        preloadFlag = true;
    }
}