Now I grant you that Microsoft put a lot of energy into .Net, and it has achieved some success. But I look at that as more of a sustaining effort. Microsoft has always had programming tools aimed at certain sections of the business market. They have changed the tools, so what used to be done with VB and Access is now done with C# and SQL Server. But fundamentally it doesn't seem to me to be a radically new market, nor do I see much evidence that their market share has changed significantly.
As for Xbox and Bing, I absolutely agree with you that they are very similar stories. Just as Microsoft used the Xbox to try to neuter Sony, they are using Bing to try and undercut Google. It will be interesting to see how that goes. I think that Google's recent stock price is evidence that the market thinks there is a real threat.
However the bigger threat to Microsoft is coming from Apple. And Microsoft is nowhere to be seen in that space. Furthermore despite the threat to Google from Microsoft, there is more of a brain drain from Microsoft to Google than vice versa. And I see more entrepreneurs worrying about competing against Google's offerings than Microsoft.