An easy bit of Ajax / Javascript

This is a fun one I wish I had the time to hack together myself, but I don't - so here you go. I have a database with a few thousand car makes and models in it which I need a user to select without resorting to a 33,000 item drop down list or a three step form OR without hiding 33,000 entries in the page. In other words - use **AJAX**. I need someone to write me some ROBUST javascript (i.e. maximum browser compatability) that will populate my drop down lists accordingly. The form will consist of these select boxes: [MAKE] - when changed will trigger Ajax to populate: [MODEL1] - when changed will trigger Ajax to populate: [MODEL2] So, changing [MAKE] will reset MODEL2 to 'empty' and disabled. Changing MODEL1 will populate MODEL2 and enable it. I don't need you to write the PHP that will get the data out the database, that will only take a minute to put together here, but I do need you to define exactly how you want the data to be returned to your script. I will be most impressed by the coder who can create code that will gracefully degrade to some alternative method for browsers that aren't capable of supporting Ajax methods (e.g. three steps in a popup or ilayer that set the value of hidden fields to produce the same result). ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform As many modern browsers as possible on as many platforms Javascript / Ajax methods with XMLHttpRequest