Right-click the HTML file, select "Open With" and then click "Notepad." The file is opened in Notepad. Click "File" in the top left corner of the window and select "Save As" from the drop-down menu.

Do you get annoyed when you want to save something in Windows Notepad with an extension other than .txt (like .sh or .conf) and you have to use up an extra two clicks selecting 'All files'?