var totalItems = 0;
var itemsPerPage = 8;
var pageNum = 0;

function productsUp() {
  //new Effect.Move($('productThumbs'),{x:-10,y:0,'duration':1,'mode':'relative'});
  if( pageNum != 0 ) {
      jQuery('#productThumbs').animate({'top':'+=460'},500);
      pageNum--;
  }
  updateCounter();
}

function updateCounter() {
  var lastItem = (itemsPerPage * (pageNum + 1));
  if( totalItems < lastItem ) {
      lastItem = totalItems;
  }
  var firstItem = pageNum * itemsPerPage + 1;
  jQuery('#pagecounter').html('Items ' + firstItem + ' - ' + lastItem + ' of ' + totalItems);
}

function productsDown() {
  var totalPages = Math.ceil(totalItems / itemsPerPage);
  if( pageNum < totalPages -1 ) {
      jQuery('#productThumbs').animate({'top':'-=460'},500);
      pageNum++;
  }
  updateCounter();
}