function changePreview(tabNumber) {

var tabNames = ['howitworks','success','costsandfees','getstarted','specialoffers','relatedproducts'];

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';
}