function Form1_Validator(theForm)
{

 if (theForm.firstname.value == "")
  {
    alert("Please enter your first name.");
    theForm.firstname.focus();
    return (false);
  }

 if (theForm.lastname.value == "")
  {
    alert("Please enter your last name.");
    theForm.lastname.focus();
    return (false);
  }

 if (theForm.email.value == "")
  {
    alert("Please enter your email address.");
    theForm.email.focus();
    return (false);
  }

  if (isEmail(theForm.email.value) == false)
  {
    alert("Please enter a valid email address.");
    theForm.email.focus();
    return (false);
  }

}