Ajax Register - Conditional Drop down menus

Can ajax create conditional drop down menus and if so how? For example during registration a user would choose a California, New York, Chicago for the state. Based on that a seccond drop down menu will list city, so for California the list would be Los Angeles, San Francisco, Other. The second drop down menu would have to be populated before the user completes the rest of the form and clicks submit.

Also I'm using AEC and Community Builder on my site. They are working well together. And I'm concerned that adding in Ajax Register will cause errors and problems. There's no trial version for AJAX register and I don't want to pay for it only to find I can't use it. Does anyone have experience using AJAX register with AEC and CB? (I'm currently using CB for registration, but it doesn't offer conditional drop down menu. )

No you can't add any additional fields (except Terms of Service which will be available in next version) and no, it won't work with any 3rd party component. Please ask you 3rd component provider to provide you with the additional feature you need. AJAX Register is replacement for the core registration component only.