Microsoft will do well for along time. But I still wouldn't put shares in them, I still think because they are so big, down is the main direction and Google is on the up overall.
However as great as Google is don't count MS out, The only part of MS that makes money is the OS and the software like Office AFAIK, Zune, Xbox, Windows Mobile etc all lose money.
(a lot depending on the new Windows phone)
However the OS is in such a strong position they can't fail. People need Office, people need Windows, there is no alternative.
Apple or Google have no where near the features required for business use.
But I do think these 2 will become more popular with "light" users now everyone and their dog is on the net.
Apple for the people that want to pay and look cool, Google for the cheapskates that don't mind selling their privacy.
Just don't put any in Linux!
I think all 3 will be perform greatly, I would spread my shares over them all and just hope the software industry develops faster than other industries. It probably will do pretty well. these companies are pretty diverse also, Google is getting into renewable energy and Internet connections now!