"Network-attached storage (NAS) offers an alternative to
traditional fileservers by creating systems designed specifically
for data storage. A NAS box generally runs an embedded operating
system (OS) rather than a full-fledged network OS, and it requires
no monitor, keyboard, or mouse. One of the simplest NAS setups is
Server Elements' NASLite.
"NASLite is a diskette-based Linux OS that can convert any PC
into a dedicated fileserver. With it, you could create a NAS box
out of an old 486 machine with 16MB RAM, a diskette drive, one to
four IDE hard drives, and a network card..."