function Updatemainform()
{
  var makeSelect = document.forms.mainform.make;
  var modelSelect = document.forms.mainform.model;

  modelSelect.options.length = 0; // Clear the popup

  if (makeSelect.options[makeSelect.selectedIndex].value == "audi")
  {
    modelSelect.options[0] = new Option("Please choose a model");
    modelSelect.options[1] = new Option("A3");
    modelSelect.options[2] = new Option("A4");
    modelSelect.options[3] = new Option("S4");
    modelSelect.options[4] = new Option("TT");
  }
  if (makeSelect.options[makeSelect.selectedIndex].value == "seat")
  {
    modelSelect.options[0] = new Option("Please choose a model");
    modelSelect.options[1] = new Option("Leon");
    modelSelect.options[2] = new Option("Ibiza");
  }
  if (makeSelect.options[makeSelect.selectedIndex].value == "skoda")
  {
    modelSelect.options[0] = new Option("Please choose a model");
    modelSelect.options[1] = new Option("Octavia");
    modelSelect.options[2] = new Option("Superb");
  }
  else if (makeSelect.options[makeSelect.selectedIndex].value == "vw")
  {
	modelSelect.options[0] = new Option("Please choose a model");
    modelSelect.options[1] = new Option("Beetle");
    modelSelect.options[2] = new Option("Bora/Jetta");
    modelSelect.options[3] = new Option("Golf/GTI");
  	modelSelect.options[4] = new Option("Passat");
  }