For general things i like Windows XP and Windows 2003 Server but when people like to create powerfull aplications (integer processing) they use Linux (Red hat , Fedora debian) is easier to cluster linux PC's than windows pc's , linux is very good and is getting better each day china and japan are building a new variety of software for linux so it is matter of time when you will have all kind of software running on linux , then will be just taste to decide which one you like .