visual basic and microsoft's speech recognition engine might suit you well. finding a project in the open domain that you like and are able to edit to your needs will probably take a lot more effort than creating your own. animations can be done in flash and integrated into the app to have a smooth look to it. or if someone else (perhaps v_ln) can point you towards a voice recognition engine for flash, then go with all flash. it seems like a rather fun project to play with, please do show updates if you decide to create this yourself.