Where's the cow? (Er, beef?)

Ever wonder why we call lamb "lamb" and fish "fish," but why we call cow "beef," pig "pork," and chicken and the like "poultry?"

Well, me too. Turns out the answer is, likely, that no one's sure of the answer. But you can find some discussion on the matter right'chere (you'll need to cut 'n' paste, as link function is on the fritz):

http://www.straightdope.com/mailbag/mmuttonpork.html