Voyager, two reasons of using Windows in office, here in Russia, are 1C:Enterprise (for accounting, storage, trade, human resources mamagement, and so on) and ConsultantPlus (full collection of Russian laws). Then it's like an avalanche - all this require at least one Windows Server... er.. I hate it!
Both program complexes exist only as windows applications, in spite of constant promises of developpers to release linux versions. And the only reason why people use Windows at home is... playing games.