Basically, the box is a hard drive toaster-like thing –it's empty on delivery and you select what capacity parallel ATA (PATA) disks you want inside. The box holds two drives but it will work with just one (although some of its potential features will be diminished). They can even be different capacity drives.
The difference between using Storage Central and just stuffing the extra disks into your computer is that Storage Central acts as a node on your LAN. The brain behind the box is Zetera's Z-LAN technology, which attaches the drive to your network. Any access to the data on the drive is done through the network, directly to the Storage Central Unit, not through anyone's computer.
Technically, the concept is called storage over IP (SoIP) and it's a variation of the storage area network (SAN) devices used by the IT Big Boys to hang printers, disk drives, tape units and the like on their networks. NetGear, however, using Z-Lan, removes all of the hassle and worry from being attached -- as well as any extra gateways and protocols and everything else that draws sweat from the beaded brows of IT managers.
The most difficult part of installing Storage Central is deciding what capacity drives should populate it. That will depend on what you'll be using it for –to share data, music, video, or any of an endless list of possibilities, with others on your network. Thanks to the influx of serial ATA (SATA) drives, PATA devices are now relatively cheap and plentiful, giving you the opportunity to attach 640GB to your network for around $400, including the bare Storage Central unit. There's no need to stop there, either. You can add more Storage Central boxes, with more hard drives, to manage more data.
Physically installing Storage Central requires sliding your choice of drive(s) into the box (there are no rails or screws needed for that; the interior is separated into two compartments) and attaching the data and power cables, connecting the box itself to your network with the supplied Cat 5 cable, and then plugging it into an AC outlet. The magic begins with the Storage Central Management Utility software.