The Boycott Bush campaign lists the top 30 donors to the Republican Party with global consumer brands. Microsoft is number three with a donation of $2.4 million. The call to boycott these brands is in response to the US rejection of the Kyoto agreement.
Microsoft used to be politically agnostic but the whole Department of Justifice affair certainly taught it that it couldn't be. It's now a politically savvy player and like most corporations, it's busy currying favour on Capitol Hill and donating money to both sides.