Window 7 with Service Pack 1
There are rumors in cyber world that Microsoft is going to release windows 7 SP1 at the end f this year 2010, moreover, there are reports saying that the new version is ready and currently in the beta testing phase.
According to anonymous source at TechARP.com (Malaysian website which has been accurately predicting different patches and service packs for Microsoft products) many previous bugs have been fixed resulting increase in performance.
With sale figures exceeding 90 million copies the launch of win7 with SP1 can attract more potential customers especially big corporations.
At this point of time Microsoft hasn't confirmed or denied this rumor