Html is Html there is no such thing as Firefox html, or IE html its just html. If you are getting icons with the FF logo, that just means FF is associated to open the file on a double click but it does not in any way preclude IE from opening them.
If you want to change the icon to IE's html icon, holding the Shift while key right clicking on an file, will add one more option to the menu. "Open With" select the Open With option, Click on the Choose Program button. Select IE, and Tick the box that reads "Always use selected program to open this kind of file". IE will then be set as the default to open the file type.
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Ignorance is not necessarily Bliss, case in point:
Unknown has caused an Unknown Error on Unknown and must be shutdown to prevent damage to Unknown.