image1 = new Image();
image1.src = "images/btn_home_+.gif";

image2 = new Image();
image2.src = "images/btn_services_+.gif";

image3 = new Image();
image3.src = "images/btn_resources_+.gif";

image4 = new Image();
image4.src = "images/btn_contact_+.gif";