Microsoft's IE8 has been designed to be customized by the person using it. The first time the user opens IE8, it allows the user to build the browser to hold the features that are relevant to the user.
Another important part for IE8:
"IE will never install, or become the default browser without your explicit consent. However, we heard a lot of feedback from a lot of different people and groups and decided to make the user choice of the default browser even more explicit. This change is part of our ongoing commitment to user choice and control."
Read the full article at eWeek here.