>When you look at HKEY_CLASSES_ROOT\.doc, the Default value is Word.Document.8. But then, as outlined in the first link I listed earlier, you have to chase down another key to get the friendly name. In this case you would go to HKEY_CLASSES_ROOT\Word.Document.8, and you see that the Default value is "Microsoft Office Word 97 - 2003 Document", which is the friendly name.

No, the default is Value not set. This is why I assume Firefox uses something on its own.