function toggleTextbox() {
	var other = document.getElementById('other');
	var textbox = document.getElementById('textbox');
	
	if ( other.checked ) {
		textbox.style.display = 'block';
	} else {
		textbox.style.display = 'none';
		textbox.value = '';
	}
}

function validateForm() {
	var form = document.signup_form;
	var valid = true;
	
	if (form.txt1.value.length == 0) {
		alert("Please enter your name.");
		form.txt1.focus();
		valid = false;
	} 
	else if (form.txt2.value.length == 0) {
		alert("Please enter your job title.");
		form.txt2.focus();
		valid = false;
	}
	else if (form.txt3.value.length == 0) {
		alert("Please enter your company.");
		form.txt3.focus();
		valid = false;
	}	
	else if (form.txt4.value.length == 0) {
		alert("Please enter your postal address.");
		form.txt4.focus();
		valid = false;
	}
	else if (form.txt5.value.length == 0) {
		alert("Please enter your telephone no.");
		form.txt5.focus();
		valid = false;
	}
	else if (form.txt6.value.length == 0) {
		alert("Please enter your email address.");
		form.txt6.focus();
		valid = false;
	}
	else if (form.txt7.checked == 0 && form.txt8.checked == 0 &&
			 form.txt9.checked == 0 && form.txt10.value.length == 0) {
		alert("Please check at least one of interest or if other specify one of your own.");
		form.txt7.focus();
		valid = false;
	}

	return valid;
}