High performance computing with respect to personal computer (PC) clusters is presented. The requirement of performance and the availability of resources is addressed through an innovative synergy of new and old ideas of parallel computing community. The low cost technologies from the consumer digital electronics industry are also addressed. The legacy concepts are presented as the physical clustering of hardware resources and the abstract message-passing model of distributed computing. The low cost computing is derived from the mass market commercial off-the-shelf (COTS) PC and local networking industries.