Microsoft's seen the inside of a courtroom many times, and it's often been much-smaller companies who have launched successful lawsuits.
In 2003, a small U.S.-based tech company accused Microsoft of patent infringement, and were awarded damage of more than 500 million U.S. dollars. In August 2006, Microsoft was ordered to pay Z4 Technologies 140 million dollars for another patent infringement case.
In April 2009, a Singaporean software developer was awarded nearly 400 million dollars, again for breaches of intellectual property. To date, Microsoft has been involved in more than 110 U.S. patent lawsuits, and 24 from the beginning of 2009 to August 14th this year.