recently I have been assigned a task where I have to open Microsoft Word’s file in Web browser for customer to edit them. For this I got a reference of this article

  http://support.microsoft.com/kb/311765

And believe me its really a Superb thing to do, I am very impressed with this ActiveX control. (There is no other way mind it) to make complete office work from your web browser. And this is better to have than a CMS editor for very restricted MS Word lover customer.