What it’s probably offering is an easy solution — plug it in and you’re off. I think Microsoft panicked when Linux owned the HPC market and Apple was getting big on plug and play HPC systems. Windows HPC is supposed to be as easy as OS X with XGrid, but I doubt it.
An "easy solution" HPC machine... That's part of what's wrong with the computer industry, IMO.
Computers and computing are inherently complicated and difficult things. I think the perpetual marketing mantra of "easy" only does us harm in the long run. It makes CEOs wonder why IT budgets are so big. It makes accountants wonder why they can't get the monstrously complicated report the just had you create subtotalled by a different column in about 15 minutes. After all, the stuff they just paid Microsoft scadillions of dollars for is supposed to be easy, isn't it? So go get me my report!
If an organization doesn't have, or is unwilling to pay for, people with enough expertise to put a Linux / Beowulf solution together (there's plenty of documentation for it on the web these days), then I'd argue that they probably don't have the expertise to be using the system at all.
...but that's just me.