Why not NT clusters? Need arguments.

[Jon Tegner]

In a disussion of clusters I got the question why not using systems
running microsoft NT. I only came up with cost and stability in a
sweeping way, and I couldnt present more quantitative arguments. Later,
I even found that an nt cluster sits on place 207 on the top500 list
(see http://www.top500.org/lists/TOP500List.php3?Y=2000&M=06)
is that an exception, or are there many of these beasts around?

I would appreciate to be enlightened on this issue.

Thanks,

/jon