function CheckForm() {

  if (document.contact_form.contact_name.value=="") {
   alert("Please fill in your full name.");
   return false;
  }
  if (document.contact_form.contact_company.value=="") {
   alert("Please fill in your company name (or repeat your name).");
   return false;
  }
  if (document.contact_form.contact_email.value=="") {
   alert("Please fill in your email address.");
   return false;
  }
  if (document.contact_form.contact_website.value=="") {
   alert("Please fill in your website URL.");
   return false;
  }
  return true;
}