Sorry, but this is not correct! Please have a look at the TOP500 to see for yourself what these machines actually compute. Unless you're not an IT professional I tell you there are things you cant achieve with a hommade cluster of PS3's or something thelike. Supercomputers from Cray for eg.g have a very specialized BUS to transfer data between units. It's not possible to have the same rates by simply connecting ordinary PCs via ethernet. You need special transport systems (BUS), special boards, management capabilities, enclosures, operating systems, etc. to do the really big computing. Think about weather prediction, the calculation of climate models or e.g. media analysis and distributed compiling.