Changing the default browser doesn't change anything outside of which browser starts when you double click on an HTML document or when another program tries to start the web browser externally. Programs that use IE internally will continue to use IE to render HTML internally, so nothing will break. It's even safe to remove IE from Windows 7 or 8, provided that you use Microsoft's add and remove features tool, since it only removes the web browser and leaves the bits that programs use internally installed.