if(document.images){
  pic0 = new Image();
  pic0.src = "images/nav_buttons.jpg";

  pic1 = new Image();
  pic1.src = "images/nav_res_on.jpg";

  pic2 = new Image();
  pic2.src = "images/nav_vgal_on.jpg";

  pic3 = new Image();
  pic3.src = "images/nav_cworks_on.jpg";

  pic4 = new Image();
  pic4.src = "images/nav_cont_on.jpg";

  pic5 = new Image();
  pic5.src = "images/nav_home_on.jpg";

}

function highlight(imageName, imageFile) {
  if(document.images)
    document.images[imageName].src = eval(imageFile + ".src");
}