if (document.images) {
  h1image_off  = new Image(); h1image_off.src  = 'devpaks-top.gif';
  h1image_over = new Image(); h1image_over.src = 'devpaks-top-high.gif';
}

function turn_off(ImageName) {
  if (document.images != null) {
    document[ImageName].src = eval(ImageName + "_off.src");
  }
}

function turn_over(ImageName) {
  if (document.images != null) {
    document[ImageName].src = eval(ImageName + "_over.src");
  }
}