WCF,
The NAS box presents its storage to a networked PC as a logical volume, irrespective of how the disks are configured in the NAS box. The networked PCs have no visibility of how the disk(s) in the volume are arranged.
If the NAS box accommodates 2 drives, supports RAID 1 and the operating system of the network clients (CIFS for windows - or the older SMB) that will access it then that's all you need.
SATA disks can be used in a RAID 1 configuration, either in hardware - i.e. at the disk controller level - or in software, i.e. at the operating system level. Depends on the NAS box.
Traditionally, hardware RAID was only implemented on SCSI controllers, because of the ability to address multiple physical disks - which the IDE Parallel ATA (PATA) interface didn't support - as you know, only 2 disks per IDE channel.
With the introduction of Serial ATA, an alternative to SCSI became possible.
SD