It's worse than that. IBM is pushing Linux on all of its hardware that Windows won't run on at all. The PCs are still being shipped with XP, for now.
But consider that every Unix server replaced with Linux is still a loss to Microsoft, because they'd sell at least 3 or 4 server licenses for Intel servers to replace one Unix box. MS is kaput in the server room and they know it.
And now Linux is intruding on the desktop.
Microsoft's worst enemy is its own licensing practices. Particularly where small business is concerned, the costs are spiraling out of control, and these guys are waking up to the fact that if they don't get out NOW it's going to be much more expensive in the future. MS is more likely to cut the big corporations a deal to keep them locked in, but they're going after the small guys with license audits and three-year upgrade cycles.
MS has no choice, really. Their market is saturated and nobody wants to keep buying the same old stuff over and over. MS is moving toward a subscription-based revenue generator, and that's why they're pushing DRM and.NET and Palladium. Once they can control the customer's access to his own data, he must keep paying up or he's out of business.
Yup, IBM gives Linux what many big companies say they need to take it seriously - a company that will service it for them.