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) {
                Button1_over = newImage("../pics/Button1-over.gif");
                Button2_Button1_over = newImage("../pics/Button2-Button1_over.gif");
                Button2_over = newImage("../pics/Button2-over.gif");
                Button3_Button2_over = newImage("../pics/Button3-Button2_over.gif");
                Button3_over = newImage("../pics/Button3-over.gif");
                Button4_Button3_over = newImage("../pics/Button4-Button3_over.gif");
                Button4_over = newImage("../pics/Button4-over.gif");
                preloadFlag = true;
        }
}