My goodness, I can't believe so many people have replied to this thread. I never would have expected such a turnout; truthfully I had nearly forgotten about the thread I want to thank you all for your opinions and your discussions.
Unless I am further swayed, what I have discerned to be Muppets is any characters that are the brainchild of Jim Henson himself, save for the Fraggles, anything created in the Creature Shop, and any of the things created for commercials/advertising. Also, I consider animated versions not to be Muppets but simply incarnations of them.
I imagine I will receive much argument on this, so let the posting continue!