Tape based backup?

I'm new to the ReadyNAS product but have a ReadyNAS Pro Business Edition that I'm now responsible for managing. Its only a small company (10 users) so I've set it up as a file server with the NAS handling all the logins/permissions etc. The only thing external I have added is an APC UPS.

I need to put in place a backup system that will allow me to take the media off site for safe storage. In the past on the Windows and Novell servers I have managed I have used a tape system, doing incremental backups during the week and partial or full backups at the weekends, but its been quite a while since I have done any of this so my knowledge is a little out of date. The ideal system would be a tape drive I can connect directly to the NAS and software running on the NAS that would perform scheduled backup then all I or my boss would need to do was remember to swap the tapes at the appropriate time.

Can anyone recommend a way to do this for the ReadyNAS, I'm looking for a suitable tape drive and software (I have now knowledge of the Backup Exec, or Rsync)

Thanks