Really easy, functional and a real perfomer!!! After loosing our time with soho NAS solutions linke EMC/IOomega and Linksys, we put and old Intel Atom with 512 mb. ram and two 1 Tb. sata disks and an Intel gigabit ethernet card. It works like a charm. Even performs better than 500 dolar "cheap" NAS solutions. You surely want raid2 and surely want the small footprint and requirements. Nas4free saved the day!! I really reccomend you give it a try when plannig a custom and also cheap NAS solution.
nas4free is not stable, not intuitive in any way, hard to navigate and configure, and doing anything in the shell is nearly impossible. I recommend FreeNAS, it has more functionality, is more stable, and allows you to use the shell.
There are no 2 star reviews.