if (document.images) {
  butt1on = new Image();
  butt1on.src = "media/up11.gif";
  butt1off = new Image();
  butt1off.src = "media/up10.gif";
  
  butt2on = new Image();
  butt2on.src = "media/up21.gif";
  butt2off = new Image();
  butt2off.src = "media/up20.gif";
  
  butt3on = new Image();
  butt3on.src = "media/up31.gif";
  butt3off = new Image();
  butt3off.src = "media/up30.gif";
  
  butt4on = new Image();
  butt4on.src = "media/up41.gif";
  butt4off = new Image();
  butt4off.src = "media/up40.gif";
  
  butt5on = new Image();
  butt5on.src = "media/up51.gif";
  butt5off = new Image();
  butt5off.src = "media/up50.gif";
  
  butt6on = new Image();
  butt6on.src = "media/up61.gif";
  butt6off = new Image();
  butt6off.src = "media/up60.gif";
  
  butt7on = new Image();
  butt7on.src = "media/up71.gif";
  butt7off = new Image();
  butt7off.src = "media/up70.gif";

}

function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

function turnOff(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "off.src");
  }
}