[jQuery] Determine which radio button (if any) is selected on form load.

[Swatchdog]

I have an order edit form that is fed from Coldfusion/SQL that shows a
radio list of possible product selections. If the customer is editing
an order that has already been submitted, one of the products in the
radio list is selected. If it is a new order, none is selected.

Upon load, I need to determine which one, if any, is selected so that
I can turn manipulate other elements on the page.
 The div for the radio input list is id = ItemList.

This below does not work, it returns "Undefined" in the alert box.

$(document).ready(function() {
        alert($("#ItemList:checked").val());
});

Can someone throw this jPup a bone?

Thanks
SWimmer