Not sure about inserting Theorem-like environment

I'm still not sure how to insert a theorem-like environment. I hope when I 
insert a theorem like environment, emacs can promp for options (the short 
description of a theorem or definition. esp. useful for a definition 
environment.) and for labels.  I use some suggestion from reftex, but seems 
it doesn't work well.  I cannot find suggestions from AUCTeX document.

My configurations in .emacs:

;; AucTeX hooks
(add-hook 'LaTeX-mode-hook
   (function (lambda ()
        (flyspell-mode)
        (LaTeX-math-mode)
        (TeX-source-specials-mode)
        (outline-minor-mode)
        (LaTeX-add-environments
         '("lem" LaTeX-env-label)
         '("thm" LaTeX-env-label)
         '("defn" LaTeX-env-label)
         '("cor" LaTeX-env-label)
         )
        )))
and the configurations for RefTeX:
(setq reftex-label-alist
      '(("thm" ?h  "thm:" "~\\ref{%s}" t ("theorem" "thm.") -2)
        ("lem" ?l  "lem:" "~\\ref{%s}" t ("lemma"  "lem.") -3)
        ("defn" ?d "def:" "~\\ref{%s}" nil ("definition" "def.") -4)
 ("cor" ?c  "cor:" "~\\ref{%s}" t ("corollary" "cor.") -5)
        ))

What else do I need?  Thanks.

BTW: I'm using AUCTeX 11.55
                         MikTeX 2.4
                         CVS Emacs 21.3.50.1
                         Windows XP.
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Best Regards,
Adam