Self-built NAS how-to anywhere?

Hi,

I'm looking for some reasonably simple instructions on how to build a
NAS-box from scratch. The result should be something like the
Tera-Station
(http://www.buffalo-technology.com/products/network-storage/terastation/terastation-pro-ii/),
just not as expensive.

Could anybody point me to some "how-to" on the internet?

I should add that I'm not completely clueless as to hardware assemblage,
just would appreciate some inputs on selection of parts and software.

Emphasis would be on low energy consumption and noise level.

Cheers,

Jesco