IMHO, these are not the only reasons you should be worried about. Pushing more microsoft proprietary software into local government means more your tax dollars will go to usa (not to usa government, probably, since there are so many tax schemes available).
On the other hand integrating open source software in organizations usually done with help of local companies, meaning your tax dollars spend on work your neighbor do. Since in this case you are not paying for "product", you are paying for integration of open source software. (as a bonus, it often also saves bucks on software products, even if you pay more for integration/training).
ps: not saying that during process of integration of open source software often changes/bug reports/feedback contributed back to open source community, which benefits all people...