And how. My company relies on a lot of in-house software that was built against Microsoft technologies from the 1990s, and are still supported. We have plenty of resources; we could port/rewrite them if we needed to. But that isn't cheap, and I imagine we've saved a lot of money over the years thanks to Microsoft's devotion to backward-compatibility on Windows. Not just development cost, but cost related to software defects we have not created because we've been able to leave already-working software in place.

(Web applications that rely on ActiveX, on the other hand. . .)