//Preload Background images and mouse over images
    image1=new Image(62,66);
    image2=new Image(62,66);
    image3=new Image(62,66);
    image4=new Image(62,66);
    image1.src="images/sub-mastectomy-over.jpg";
    image2.src="images/sub-nursing-over.jpg";
    image3.src="images/sub-stockings-over.jpg";
    image4.src="images/sub-other-over.jpg";