So Apple passed Microsoft in market cap the other day, and the really interesting thing about it was that it wasn't really bubbly stock market frenzy that did it. Apple is trading at a 21.50 P/E which isn't absurd, even if it is higher than Microsoft's.
Why is Microsoft stalling? Because they already won.
Some years back, before she was fired from HP, Carly Fiorina made a remark about the future of HP to the effect that since the market for PCs is pretty much completely saturated already, you can't really expect the tech sector to outgrow the economy as a whole. Companies are already spending all they can on IT. There's a soft ceiling somewhere, for how much of your revenue can go into tech spending and the corporation is approaching that level.
Microsoft gets all it's revenue from this no longer expanding slice of tech spending, so there is simply no way to grow beyond the few percent of general growth.
The deflationary power of technology can push these limits a little, but the key deflationary force these days isn't the PC as such but rather the internet and the networking of businesses.

Apple on the other hand has a lot of market share to gain in laptops and phones. The only saturated Apple-market is digital music players.