I didn't take it as sermonizing. You're right, applications don't need to be changed every two years, that's only the perception MS wants you to have.
Having tracked the progress of some open source projects(JDOM, for one), they weren't appreciably slower, but they were a little slower. Also, I used to work with content management systems and open source systems were not very good. You can't really find alot of open source business software, like ERP or Logistics Control systems. But, yeah, at the OS and basic office app level, open source is getting even bigger.
Dvorak had a couple of columns on how screwed MS would be if open source developers, Intel and Apple ever got together. Ballmer would be burning his shares for heat then, they'd be so worthless.