"No mac is currently the fastest computers, but this one http://www.arc.vt.edu/arc... is pretty fast, the fastest cluster put together by a university at one time. It's common in accedemia and the government to use XServs as clusters like this because it has Xgrid, the easiest to operate grid software. Every US Navy sub also has 39 Xservs in a cluster sitting on it to run the sonar analysis software, both for Xgrid, and because it's one of the quietest rack mounted servers available; important on a modern sub." - τorƍue