All of your job defs, your media set defs, your schedules, if you have partitioned a loader - all your partition defs, the number of installed options and their serials (tho this is also in BESERNUM.XML or .TXT)
basically every thing that BackupExec knows, except the catalogs and job logs
if you use MSDE, BackupExec creates a backup every night called BEDB.BAK that can be used to recover a system