LCD/Plasma for living room and TV gaming is fine, because you sit back from the screen. It a cab it makes things look very blocky, as you are often very close to the screen. Of course if you play 3D games or emulators (ZiNc, etc) you can jack the resolution up for some very clear and pretty gaming.
Otherwise as mentioned, take note of the resolutions available. Many cheap LCD and Plasma TVs are standard def only, which means they are often physically limited to 480 "lines" (pixels, on a digital display) in height. Considering you pay a premium for a LCD TV due to the inputs and tuner (which you probably won't use in a cab), you're likely to get a larger screen with more physical pixels for less money if you go the PC monitor route.