Its Official, Windows 8 OS is on track to Release to Manufacturing (RTM) by first week of August and as expected will reach general availability by end of October. Microsoft recently announced the upgrade plans. All XP, Vista and Win 7 users can upgrade to Windows 8 at a special price $39.99 only for special period. Even those who are using Windows 8 Release Preview can upgrade with a valid license. You have these Windows 8 editions to choose Windows 8, Windows 8 Pro and Windows RT.