if you get the plasma, there is a burn in protection mode in the user settings, this is a maintenance feature that keeps the screen clean, also set the pixel movement to 4, that ensures that anything stationary on the screen will shift 4 pixels over and back so the stationary object will never be in one place, the first 100 hours on a plasma is critical to always use these features, it was created to take care of burn in, I recommend getting a LCD, they are much better for gaming and then you don't have to worry about burn ion, the LCD are hard to burn in, unless you just keep a stationary screen all the time
Thinking of getting Samsung PN50A550 50" Plasma TV, it's for basement so I like plasma price, viewing angles and not too worried about LCD brightness since it's bit dark there... Should I worry about plasma burnin if I ocasionally play Xbox 360 on it? Or should I be getting a 46" LCD isntead?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic