There were two studies conducted by McKinsey, that both led to the result that an Open Source/Free Software desktop was feasible and a strategy that is saving the AA costs, but the powers that now be seem to disregard any evidence that suggests sticking to the solution currently in place there, because someone from MS seems to be sending in black suitcases... it's disgusting.
On top of that, they're considering switching to Windows XP now, and to a Windows 7 and Office 2010 setup later on! Migrating platforms twice within two or three years (XP support ends in 2014, mind you). This is just utterly insane.