function Validator(form) { 
if (form.firstname.value == '') {
	alert('Please enter your First Name.');
	form.firstname.focus();
	return false;
}

if (form.lastname.value == '') {
	alert('Please enter your Last Name.');
	form.lastname.focus();
	return false;
}

var x = form.email.value;
var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9])+$/;

if (filter.test(x) == false) {
  	alert('Please enter a valid email address.');
 	form.email.focus();
  	return false;
}


form.Submit.disabled = true; 
return true; 
}