Auto change (profile) fields when select role in registration form

Hi all!

I have a custom registration form with multiple profile fields for 2 types of users (my profile fieds depend on the chosen role). Now i was wondering if the following is possible with Ajax:

1) The user select a role on the registration form (role choice on top of the form)
2) Ajax automaticaly detects (submits) the role and rebuild the form, with the correct profile fields for the chosen role

Any suggestions? Is this possible with Ajax?

Thanks in advance,
Gunther