Presumably his research group is free from marketeering types shaking
trade rags and pushing crap like NT. In fact they are running BSD.
See:
http://www.cs.vu.nl/~bal/das.html
On the subject of clusters, Los Alamos is running my code to solve the
next Elliptic Curve Discrete Logarithm problem on a network of 70
Alpha Linux machines. Various others are running on 130 Alphas
ranging from UDB's upto monster servers of the 8200 variety with
Linux, Digital Unix, OpenVMS and NetBSD. You know, the OSes that
people with real work to do use.
Rob.