if (document.images) {
blogOn = new Image();
blogOn.src = "images/header4.png";
blogOff = new Image();
blogOff.src = "images/header3.png";

newsletterOn = new Image();
newsletterOn.src = "images/header6.png";
newsletterOff = new Image();
newsletterOff.src = "images/header5.png";
}

function activate(image_name) {
if (document.images) {
document[image_name].src = eval(image_name + "On.src");
}
}
function deactivate(image_name) {
if (document.images) {
document[image_name].src = eval(image_name + "Off.src");
}
}