var leftArrowNorm = new Image(52, 49);
leftArrowNorm.src = "../images/left_arrow.gif";
var leftArrowOver = new Image(52, 49);
leftArrowOver.src = "../images/left_arrow_over.gif";
var rightArrowNorm = new Image(52, 49);
rightArrowNorm.src = "../images/right_arrow.gif";
var rightArrowOver = new Image(52, 49);
rightArrowOver.src = "../images/right_arrow_over.gif";

function imgOn(imgName) 
{
  if (document.images) 
    document[imgName].src = eval(imgName + "Over.src");
}

function imgOff(imgName) 
{
  if (document.images)
    document[imgName].src = eval(imgName + "Norm.src");
}