The book mentioned at the bottom "The Making of Microsoft: How Bill Gates and His Team Created the World’s Most Successful Software Company" is a very interesting one. It was actually the first book i read on computing history many years ago and i got hooked to it since then. I highly recommend it to anyone interested in Microsoft's early history - and i'd like to find something similar that covers their 90s history to a similar extent (the book only covers up to 1992, but the majority of it is on 80s stuff).