Note/update: For those too lazy to read the whole thing, this is about Microsoft's history. It shows their history of consciously anti-competitive behavior. It is aimed at those who have little knowledge of Microsoft's history. To learn more, read this document by ECIS: A History of Anticompetitive Behavior and Consumer Harm
It seems that some people are still doubting that Microsoft has consciously sought to undermine competition by abusing their position in the market. In fact, some are outright denying any wrongdoing on Microsoft's part, and if there was any wrongdoing then it was surely unintentional.
Sadly, such history revisionists are creating confusion about what actually happened, but this quote from a Bill Gates memo to the Office product group in December 1998 sums up Microsoft's attitude:
One thing we have got to change in our strategy – allowing Office documents to be rendered very well by other peoples browsers is one of the most destructive things we could do to the company.
We have to stop putting any effort into this and make sure that Office documents very well depends on PROPRIETARY IE capabilities.
So as you can see, Microsoft has a history of anti-competitive behaviour. You can agree or disagree that it is necessary to get the Government involved to deal with antitrust cases (Microsoft itself certainly thinks so, and they have filed their own antitrust complaints, e.g., against Google), but what you cannot deny is Microsoft's attitude and behaviour through the years.