Thanks for the info Steve. There was one other thing I forgot to ask you about.
Say if the user fills out all the form info before selecting their country (even if at the top of the form), and the current country has no zones, but the customers country does have zones. For example, my default country is the UK which has no zones, but the customer is from the USA and he's entered his two letter state abbreviation in the state field. Is there a way of getting the drop-down box to display the state that corresponds to the abbreviation entered when the form refreshes?