The weird thing is some of the SQL "logins" were copied as SQL "users" for the new database and some were not.
Here's what worked:
(1) With SQL 2000 Enterprise Manager, I went into each user and selected the new database in the database access tab and checked "public"
(2) I also had to use Query Analyzer to do a sp_changedbowner for my power user and change the database owner to 'sa'. I was then able to add the user back into NAV and in SQL add the new database as described in step 2,
(3) In NAV, I changed security from Enhanced to Standard (File > Database > Alter). I did not realize it was Enhanced...it has been a long time since I played with that!
(4) Now I was able to log on and Synchronize security.