Although I don't disagree with the idea that a large driving force behind Windows is the gaming market, there is also a sore lacking for Open Source adoption in the business world too. We even see this in MS's adoption of ODF 1.1 http://slashdot.org/article.pl?sid=09/05/04/1246249 While technically "compliant" it functionally is not.
Open Office isn't 100% compatible (as in exact conversion) with MS Office. It's darn close, but not exact.
As a network engineer, I have yet to find a solid compatible replacement for Visio as well. My customers don't want a PDF or non-visio compatible document, they want something that will open in Visio every time.
The defacto standards are just too well rooted still and will be until there is full interoperability between these apps.
When that changes, I think we'll start to see a stronger shift to Open Source apps and maybe even Linux.