The Western Digital's Red range of SATA hard disks is designed specifically for use in home and small business NAS devices. With this purpose in mind, the WD's are built for durability, power efficiency and low noise levels of just 23dB(A). Western Digital's `Intellipower' system, which uses caching, promises faster throughput than you'd expect from a 5,400rpm disk.
There is however a small downside, the poor slow file write speed means that these disks are less than ideal if, for instance, you want to habitually back up lots of documents to your NAS, But this has to be balanced by the Red's low power consumption, low noise levels and three year warranty make it well suited to its intended purpose - NAS storage. You could buy the Western Digital Caviar Green 3TB for slightly less if performance isn't so important.
Review update: 27.10.2013
Important note - I managed to attend IP EXPO at Earls Court recently and managed to speak to Western Digital people about the WD Red NAS drives, and they have confirmed what I have read on the WD website - that you should only have between 1 to 5 drives in anyone single NAS unit. If you, let us a say, have a unit like the Synology 1813+ (an 8 bay unit) you are strongly advised not place any more than 5 WD Reds in the unit. As clusters of above 5 drives will give vibration issues that can lead a drive to believe that it has `failed'. For that reason I am reducing my WD Reds in the 1813+ down from 8 to 4. The remaining 4 bays I will `populate' with WD Se 4TB drives. Obviously the decision is yours on what types of drives you use - I have decided on the WD Se drives as they have very good specification and the extra outlay is just about within my budget. Now I know, on the internet, there is some debate out there in the `forums' and blogs about this issue and its `validity' of the five drive maximum- but this is what I have heard from WD and thought best to share.