A license to print money

We learned (link in Romanian) the Romanian government is negotiating with Microsoft for a Windows XP support extension in the public administration. This is the free market at work and there may be solid arguments for doing so (yes, I would prefer my tax money to be spent on Free and Open Source Software instead of making business with a convicted monopolist, but realistically I don't expect this to happen in the foreseeable future).
My source of amazement is: once the patches and the delivery infrastructure are set for the first government (UK), then the costs for adding any subsequent government is approaching zero: computers in Romanian administration usually have Windows installed in English, so there is nothing to translate, the infrastructure to deliver patches is there and the network costs are the same or lower (presumably patches fro XP are smaller in size as patches for Windows 7).
Apparently ending support for XP makes a lot of business sense for Microsoft, they suddenly started receiving important sums of money for things they did only a week ago for free. Who would refuse that?