function validate_form() {

  valid = true;
  errors="";
  
  if (document.contactUs.name.value == "") {
    errors+="* Please enter your name.\n";
    valid = false;
  }

  if (document.contactUs.comment.value == "") {
    errors+="* Please enter a comment.\n";
    valid = false;
  }

  if (errors != "") {
    alert("Please correct following error(s) before submitting:\n\n"+errors);
  }

  return valid;

}