I’m considering either building another ITX based NAS box or to buy an off the shelf unit such as a Buffalo Linkstation or Drobo enclosure?
Drobo

I’m swaying towards the DIY option as they’re so fun to build….but those Drobo units certainly look the business!
Should I opt for a DIY solution, I’ll again be using a fanless EPIA ITX board that supports RAID and have the tiny O/S boot from CF card. I’ll probably be sticking with Freenas (http://freenas.org) as the O/S because I’ve been using it for years now and am quite satisfied that it does everything I want from a NAS box. However, i’ll also be looking at a few alternatives such as Openfiler which I haven’t used for some time now – (http://www.openfiler.com).
To keep noise levels to a mere whisper and retain as much space inside the case I’ll be using a Mini DC-DC PSU board with external laptop mains adapter like the one below -
Details of my previous NAS build can be found here -
http://stiggyblog.wordpress.com/2009/09/26/commodore-1541-disk-drive-pc-mod-part-1/
http://stiggyblog.wordpress.com/2009/09/28/commodore-1541-disk-drive-pc-mod-part-ii/