To build your own diskless workstation you need:

A boot server, and runtime server
      =>  Network boot via PXE (an Intel extension to DHCP)
      =>  Or via Etherboot/Netboot
      =>  Boot files downloaded via TFTP
      =>  NFS-share files for basic root file system
      =>  Server does not have to be Linux, but it is convenient

A workstation
      =>  Could be an ordinary PC
      =>  To network boot need either a boot ROM
      =>  Or built in PXE support in BIOS
      =>  Custom hardware for truly silent operation