"Original" username in profile...

[fly]

With Ushop, users can change their names or sometimes the admins will change users names for fun. I'd like the ability to add an original username to the profile field. I know this will require a SQL table addition and some sort of update at registration time.

How hard would this be to do? If someone can point me in the direction of a similar hack, I could probably work my way through it. Thanks guys!