There's no way to truly "migrate" a local account to a domain account that
I'm aware of (I'm sure someone will correct me if I'm wrong). But you can
create a spreadsheet, input the basics (username, password), save it as a
..csv and use csvde to import the accounts without having to go thru the
process of adding users one at a time. With only 50 users, if you don't
already have the spreadsheet, I'd say it's 6 of one, a half-dozen of the
other which would take the most time. Either way, if you want users to
retain desktop settings, application settings, etc. you'll need to visit
each computer and copy the local user profile to the domain profile for each
user.
...kurt