In this case, the startup cost is probably minimal for the usual reasons. Most students interested in such a project are likely to be running Linux on the own computers, and learning to do parallel computing is all part of the course. The Beowulf project benefits from developments in both classes of architecture. MPP's are typically larger and have a lower latency interconnect network than Beowulf clusters. In spite of vendor claims, programmers are still required to worry about locality, load balancing, granularity, and communication overheads.
Most programmers develop their programs in message passing style.
Such programs can be readily ported to Beowulf clusters. Programming a NOW is usually an attempt to harvest unused cycles on an already installed base of workstations in a lab or on a campus. Programming in this environment requires algorithms that are extremely tolerant of load balancing problems and large communication latency. These programs will directly run on a Beowulf. A Beowulf-class cluster computer is distinguished from a Network of Workstations by several subtle but significant characteristics.