my dad's office has an RS6000 for computations but when they display it they use an Apple G4 based machine ( i believe its a 500 or 600mhz).
the reason being the GL libraries for Linux (especially MesaGL libs) can get screwed up quite easily.. the Mac does the displaying quite easily...
Overall they have only 2 windows machines, one for the reception and one for something else.
Edit:
My dad does exactly what those guys are talking about in the article.. Computational Fluid Dynamics.. or CFD..
The G4 has a much higher processing than teh RS6000 but they still use the RS6000 because they spent the money on it at one time and now its quite outdated. They are thinking of making a cheap "beowulf" later with multiple P3 machines running at 1.2 ghz... its cheap and when put together in a stack of 20 or so it will outrun anything they got for the moment....
I am not sure when and IF they will put that into place.. they are quite happy running their calculations for days on end to get a result on the RS6000 or the G4.