function changePreview(tabNumber) {
      var tabNames = ['Howitworks','Reachmorecustomers','Costsandpayment','Forlocalbusinesses','Successstories'];
      
      for (i = 1; i <= tabNames.length; i++) {
        document.getElementById('infotable' + i).style.display = 'none';
      }
      document.getElementById('infotable' + tabNumber).style.display = '';

      tds = document.getElementById('infotable').getElementsByTagName('td');
      for(i = 0; i < tds.length; i++) {
        if (tds[i].className == 'active menu')
          tds[i].className = 'menu';
      }
      document.getElementById('tab' + tabNumber).className = 'active menu';
      urchinTracker('/select/Login/tab_' + tabNames[tabNumber - 1]);
    }