Some more details have filtered out ...
M$ based their cost figures on equipping the computers with WinXP and Office 2003!
So ... let's see ... let's install a stale, unstable, 12 year old, OS with more security holes than Swiss Cheese has holes, coupled with a 10 year old copy of Office ... or install a modern, up-to-date OS that is secure and free.
Sounds to me as if Munich made the right move ... and that M$ is just espousing their sour grapes over the move to FLOSS.