I should have also said, you may need to synch the login sids and add logins on the new server to allow access.

after you add logins, use the database and run

exec sp_change_users_logins 'report'

to see if you have some SID mismatches.

There is an MS proc out there for migrating logins (complete with SID information) called sp_help_revlogins. that would be another approach.

Cheers