DataTank
The encryption on the standard DataTank is hardware based and very straight forward to set up during or after initial installation. It's based on 128bit Advanced Encryption Standard and works great and you can choose how much of the capacity you wish to encrypt along with other configuration settings. The software that comes with it the 1TB version is NTI Shadow which is a good piece of software and pretty straight forward for scheduling your back-ups etc. The standard DataTank would be fine for attaching to a NAS router or directly attached to a backup server via the USB2 or FireWire, but if you're looking for a full NAS solution it may be worth considering the DataTank Gateway, ARM9 processor, gigibit ethernet and built in router(wireless if you need it) comes with NTI Shadow aswell (but no hardware encryption) Hope this helps.