We recently deployed a Netgear ReadyNAS Duo (NAS = Network Atttached Storage) in our workshop for general data backup duties. The unit is equipped with 2 x 500GB SATA drives set up in a redundant X-RAID configuration (more information on X-RAID here). The reason we have configured the unit in X-RAID rather than RAID 5 is that we also use the unit for media streaming, which X-RAID is particularly efficient at doing.
Data backup is handled by the open source Cobian Backup 9 program running on the various network computers. We like Cobian because it is free, flexible and allows backups in native file formats with or without compression.
The ReadyNAS Duo is particularly adept at media streaming as it incorporates Logitech's (formerly Slimdevices's) Squeezecenter music streaming software, as well as iTunes Server software. Note that this NAS is really a stripped down computer with 256MB of RAM running Sparc Linux. Access to Squeezcenter is via a web browser on any attached network computer. The only downside is that the web browser is relatively unresponsive, but this does not impact on streaming performance. The NAS is serving music to two Squeezeboxes and a Squeezebox radio and response time via the Squeezebox interfaces is only marginally slower than a PC-based Squeezeserver. The ReadyNAS Duo can happily serve different music to each Squeezebox or synchronize the music on any two or all three units.
We're big Squeezebox fans so more on that anon.