Convert user database

I have been asked about the plausibility of converting all of our user accounts on an NT4.0 domain from our current standard of first initial last 5 letters of the last name…BGATES for ex. to using a new convention FN.LN

My concern is user profiles from old login. Is there a known program that will help us migrate to this standard? And preserve registry entries and copy the old profile to the new profile???

Thanks
Fly