You don't say...
Thus quoth the 10K from MSFT:
The increase in Linux distributions reflects some significant public announcements of support and adoption of open source software in both the server and desktop markets in the last year. To the extent open source software products gain increasing market acceptance, sales of our products may decline, which could result in a reduction in our revenue and operating margins.
This is the most honest appraisal of the threat that open source has to MSFT's business. I guess the first step is admitting you have a problem.