I don't know where you heard that because a plasma is not good for gaming at all. It has the same kind of image flicker like the old crts had and it suffers from image burn-in meaning that if you keep a static picture on for hours it will be permanently burned to your display.
like most things it's a trade off, plasmas generally handle motion processing better than LCD's do. All the 120hz/240hz specs you see on LCD TV's are sort of a band-aid to make up for the traditionally poor motion processing of LCD's. Plasmas can burn, but really it's no more of a danger than the CRT that you grew up with. Unless you're prone to marathon game sessions it shouldn't be a problem, for AH purposes unless you're the type that likes to walk away from the game and sit in the tower for hours on end or go AFK for a long slow climb to 30k in a lancaster with all the looking around we do it shouldn't be a problem.
Most plasmas have features that will help prevent burn-in. Be it a subtle pixel shift or the ability to turn on a white screen, or some other method. I've owned a plasma for 4 years now or so which I use for my every day TV viewing, the only time I've had burn in be a problem was back during the presidential elections when I watched one of the debates that latest 2+ hours w/out commercial interruptions and the stupid CNN graphics left a bit of an after image, I turned on the white screen for a bit and that took care of it. Only time it's ever even came up.
If you are prone to really long game session with a static image on screen (like a FPS HUD or some such) then yes LCD is probably better.
