CNET News.com reports that South Korea is to promote Linux use.
It makes sense for governments to be pro Open Source. Regardless of the cost issue, open source has the advantage that it guarantees open access - in a democratic society creating barriers to participation is a significant issue.
Locking people into undocumented data formats threatens participation particularly in poor countries, but does also cause a significant archival problem once the vendor withdraws support.
However it also provides an important possibility to grow the local service and development industry.
Even if Microsoft would turn out to be right, and OSS turned out to be more expensive than their software, that wouldn't change that the alternative is to funnel money into the coffers of a US company or to funnel money into the wallets of local software engineers and IT consultants who in turn will pay a significant chunk back again in tax, and use a significant chunk of the rest to purchase products in the local economy.
These are the two reasons I think should be the most important for governments looking at open source - the cost of Microsoft software is much larger in terms of reduced opportunities and investments in the local economy than it is in direct license and maintenance costs.