In the era of personal computers, here is one day which has changed the computer universe. It is the fourth of April 1975. There are probably not plenty individuals who know the day because it is not a public holiday and PC enthusiasts do not remember it at all. It is a day of establishment of Microsoft Business. The fathers of the success – Bill Gates and Paul Allen have been recognized internationally and made many of cash but what is the most important – they have done a transformation in the PC world and modified it for better.