There is news suggesting that Apple has overcome Microsoft. According to this article, the total amount of machines which equip either iOS or Mac released in the last quarter was higher than those with Windows.
Apple Insider: Apple, Inc. sold more computers than all of Microsoft's Windows PC partners in December quarter
This graph describes mainly the rapid growth of iOS, installed in iPad, iPhone, and iPod. Actually, the sales of iOS today has increased by ten times compared to a few years before. In contrast, production of Windows PC is slightly decreasing in a couple of years.
Meanwhile, we must recognize that more than 90% of Apple products adopts iOS. Although Apple also sells Macintosh computer as a rival to Windows, the growth rate of it is still sluggish. To be honest, it is a little surprising, as I often see someone uses Mac at a cafe recently. Anyway, Windows is dominant to Mac at least for business use.
On the other hand, Microsoft has an alternative choice to win the share in mobile device users. It is planning to combine Windows RT into Windows Phone.
Know your mobile.com: Microsoft May Combine Windows & Windows Phone
Microsoft is struggling against the dilemma between newly architecture and legacy softwares for a long time, as I mentioned before. Windows RT was one of the solutions for this problem. The compatibility with old softwares was sacrificed at Windows RT. Unfortunately, the decision of Microsoft seemed to fail to gain the acceptance in the market.
My past entry: New CEO of Microsoft
The result of the battle between Microsoft and Apple is unclear. In my opinion, people will be indifferent to choose a hardware and OS in the near future. We can play Google Document on the internet regardless of the OS. When it comes to hardware and OS, both Microsoft and Apple will lose the share gradually, in my assumption.