The essential problem here is that you need to group a set of boxes and then if any one of the set is clicked, iterate through the set, unchecking all except the one that was clicked.
You can group using a class name. Then give each an id.
When the class is clicked, save the id of the clicked one. Then iterate through the checkboxes within the class and uncheck any that have a different id than the one you saved off.
<form action="">
<input id="cbBike" type="checkbox" class="CB2RBVehicles" name="vehicle" value="Bike" checked>I have a bike<br />
<input id="cbCar" type="checkbox" class="CB2RBVehicles" name="vehicle" value="Car">I have a car<br />
<input id="cbBoth" type="checkbox" class="CB2RBVehicles" name="vehicle" value="Both">I have both<br />
<input id="cbNeither" type="checkbox" class="CB2RBVehicles" name="vehicle" value="Neither">I have neither<br />
</form>
var selectedBox = null;
$(document).ready(function() {
$(".CB2RBVehicles").click(function() {
selectedBox = this.id;
$(".CB2RBVehicles").each(function() {
if ( this.id == selectedBox )
{
this.checked = true;
}
else
{
this.checked = false;
};
});
});
});