The US government claims that Microsoft has a monopoly. They have gone through great expense to convict them of this, and are still bickering
about what the remedies should be (I predict they will accomplish nothing).
A simple solution I saw suggested on the web (I have forgotten the source) suggested that if the government really doesn't want Microsoft
to be a monopoly all they have to do is stop buying software from them (since the US government is a major purchaser of Microsoft software).
If the US government obtained their software elsewhere then by definition Microsoft would no longer be a monopoly.
I would go a step further and suggest that all governments should only use open source software (since it is foolhardy to trust close source
software when national security is at stake). If even a fraction of the current governmentsoftware bugdet was spent on funding open source
software everyone (with the exception of Microsoft) would benefit.