According to a recent study by research firm StatCounter currently Windows 7 is installed on 50.2% of the computers in the world. In second place by a large margin from the other participants in the study is still in Windows XP with a share of 29.9%, and lose more of their positions.
Death of XP I think will come in 2 years. The remaining interest is divided between the cooled OS. In fact, Windows has a larger share because they do not take into account the pirates. In RF is probably 95%.