[Gaurnim]

EDIT : Looks like I haven't read the original post correctly.
Thought the problem was on the PC and not on the Mac.
Disregard the following, then.


Without going in the registry, you have the file association available in the Windows Explorer.
The following should work for both Windows XP and 2K. Can't say the exact menu names for Vista.
- Click on "Tools", then "Folder options"
- Go to the "File types" tab, and browse down to epub.
- Check what it says in "Open with"
- If it says ADE, then you can use the "Modify" button to select another application
- if it doesn't, you might want to have a look in the "Advanced" menu