I recently bought this NAS http://www.envizage.com/p/730142/dual-s ... erver.html
plus two of these drives http://www.scan.co.uk/Products/1TB-West ... 32MB-Cache
total cost about £250, but you could scale it down with the drives significantly. depends how much space you want and what you want it for. the NAS is excellent, does torrenting for you, can serve media over the network (Twiny and Twonky if those mean anything to you?) plus has a few other applications you can install. it can support IDE and SATA drive in the same device.
Its also known as the 35HD-DUAL-NAS-E. http://mrt.nas-central.org/wiki/Main_Page
manufacturer's website http://www.mrt-communication.com/qa-35HD-DUAL-NAS-E.htm
it also supports USB mass storage devices and printers via the usb port
Forum http://mrtforum.memoriedigitali.com/viewforum.php?f=12 you can install applications to it
firmware discussion http://mrtforum.memoriedigitali.com/viewtopic.php?p=290
loads of other results from Google!
the above info from my post at http://www.nwcaching.co.uk/forum/viewtopic.php?f=5&t=2550