Microsoft advises Windows users to first remove the old update before applying the new update.
That's all well and good, but what about Aunt Harriet who doesn't know diddly about computers? Microsoft really needs to make the update process transparent for basic users.
And if they move to continuous updates with major changes instead of service packs in their upcoming operating system, I foresee some marvelous screwups. Windows runs on such varied hardware, I don't believe they will be able to catch every possible conflict. They are not like Apple, with a limited hardware target.