jquery checkbox enable onload to display other elements

jquery checkbox enable onload to display other elements

http://jsfiddle.net/Q9Lg4/20/
ok, i've found an example that i've altered a bit to see if any of you
alter my example to the way i want it to work
my php page is going to load and assign the check box to either be enabled
(checked) or disabled (unchecked).
if enabled on page load. I want the fields to be enabled and allowed to
enter a variable which will be sent back to the database
if disabled on page load. I want the fields to be disabled
<form>
<input type="checkbox" name="detailsgiven" id="checkbox" checked=checked>
Enabled?<br>
<input type='text' name="details" id="tb1" value='box1'><br>
<input type='text' name="details" id="tb2" value='box2'><br>
<input type='text' name="details" id="tb3" value='box3'><br>
</form>
jquery
var check = document.getElementById('checkbox');
check.addEventListener('click', toggleDisabled, false );
function toggleDisabled(evt) {
var checked = evt.target.checked;
if(checked){
document.getElementById('tb1').disabled = "disabled";
document.getElementById('tb2').disabled = "disabled";
document.getElementById('tb3').disabled = "disabled";
}else{
document.getElementById('tb1').disabled = "";
document.getElementById('tb2').disabled = "";
document.getElementById('tb3').disabled = "";
}
}