Auto Title bio node on registration

I'm using the bio module to create a node for each user, I've got the CCK text fields 'first name' and 'last name' which appear on the registration form, I want to use these to title the node when it is created, i.e. when the user registers.

(these are the tokens - [field_first_name-formatted] [field_last_name-formatted]) - currently you have to update the node before it gets titled correctly.

fago - you mention in another request that workflow-ng could be used here, that sounds great as i use it already, but i don't know where to start. Any ideas...