if (document.images) {
  image1on = new Image();
  image1on.src = "images/tab1_on.bmp";

  image2on = new Image();
  image2on.src = "images/tab2_on.bmp";

  image3on = new Image();
  image3on.src = "images/tab3_on.bmp";

  image4on = new Image();
  image4on.src = "images/tab4_on.bmp";

  image5on = new Image();
  image5on.src = "images/tab5_on.bmp";
  
  image6on = new Image();
  image6on.src = "images/tab6_on.bmp";

  image7on = new Image();
  image7on.src = "images/tab7_on.bmp";
  
  image1off = new Image();
  image1off.src = "images/tab1.bmp";

  image2off = new Image();
  image2off.src = "images/tab2.bmp";

  image3off = new Image();
  image3off.src = "images/tab3.bmp";

  image4off = new Image();
  image4off.src = "images/tab4.bmp";

  image5off = new Image();
  image5off.src = "images/tab5.bmp";

  image6off = new Image();
  image6off.src = "images/tab6.bmp";  

  image7off = new Image();
  image7off.src = "images/tab7.bmp";  

}

function changeImages() {
  if (document.images) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = eval(changeImages.arguments[i+1] + ".src");
    }
  }
}