Backup software

I have two clients, one running W98SE, the other running W2KServer. All that either of them wants to do is perform an unattended full backup every night, rotating tapes on Seagate Travan tape drives, overwriting the tape.
The problem seems to be in getting the backup to recognize set and/or media names/labels of the tape it is to overwrite. The 98 machine is running Retrospect Express on a Seagate Travan ST-20000A USB tape drive. The 2000 Machine is running Microsoft NTBACKUP with a Seagate Travan IDE 20000A. If you need more information, please email me.