You have to start afresh..
I dont think there is a way of converting a BEWS database into an NBU daatabase, so my advice would be to keep the BEWS server alive, and replace it with a new NBU server, so that in the event of a BEWS restore request, you can use BEWS to identify the media reqired for the restore, then you can import the meida into NBU, then perform the restore.
Make sure you uninstall all Backup Exec servers, Managed Media Servers and Clients, otherwise this could have serious consequences when you try to install netbackup.
Then you need to get hold of the licences for: -
SSO for * 2 SAN attached Tape Library. ( One with 2 Tape Drive, and second with 4 tape drives)
SAN Media or Clients for * 7 servers attached to SAN (Exchange, SQL, Sharepoint etc..)
Media Server for * 2 Media Servers
Master Server for * 1 Master Server
