Is Microsoft Really Scared of Open Source Projects?

Last week, Microsoft announced to have already distributed 40 millions licenses for Vista, even though Redmond's giant did not comment on the tricks used to push OEM to replace XP by Vista, and other coupons and discounts to update to Vista.
At the same time, Microsoft announced that Open Source projects, including Linux, were violating 235 of its software patents. This came as a surprise, as Microsoft is rather known for copying good ideas from others; and Open Source leaders quickly asked Microsoft to release the complete list of violation providing details about infringements. But so fat without any serious answer. So, Open Source leaders fired back to Microsoft, claiming that this announcement was simply untrue, and that Vista code was probably also using parts of instructions or technologies protected by third-parties patents; especially taking into account the amazing number of patents issued for concepts or featuring broad claims.
It seems that Microsoft is not really willing to directly attack Linux and Open Source, but rather push companies using such solutions to move to MS-branded products or support potential legal actions.