My gut feeling is Debian for bog-standard compute nodes, because it has no commercial agenda, and will not be shot in the head because of such agendas. Plus, of course, the fact that it's a damned fine distribution anyway (OK, I'm a bit biassed, I used to be a Debian developer). For machines where compatibility matrices are important (such as machines to run Oracle), it'll probably Red Hat Advanced Server, or the SuSE equivalent, and ponying up the dough, unfortunately. Tim -- Dr Tim Cutts Informatics Systems Group Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK