Tokyo Tech Tsubame Sun HPC Cluster

that's because that scale is rated in TF of overall power. The best part of Tsubame is that it is made from completely commercially available parts in a cluster configuration.

Why exactly do people buy from major vendors (i.e. Sun MicroSystems) if the clusters are built using commercially available parts? Couldn't they (research labs) build their own from scratch? I mean the people buying these badboys are either scientists They could design their own nodes and then rack'em in a configuration could they not? (I'm new to this.)

yes, they could take the time, energy, and resources to build a supercomputing cluster, but for alot of corperations, it's more ecconomicly viable to purchase them, already built from another computer. Same goes with average PC's, but a lot of people are still buying Dell's aren't they?

Why don't people build their own airplanes?

This is half a million dollars worth of hardware.

Simulations of planetary collisions and massive explosions in real time don't just happen because you plugged a bunch of motherboards together.

Those aren't pretty video game graphics, those are mathematically correct models that can be studied in very reliable detail.