AE has a very nice preset ratio log for the stage settings. If you have AE… Although it would depend on what you were going to use the effect or project for I guess. Nevermind…
why woul you use a tv card if a plasma screen has a vga port all you need is a vga wire with both ends the same as the one you connect to your vga card from your monitor, as for dimensions its all relative i designed a flash presentation ran it on a plasma at 800x600 res on the pc and it looked great oh and it was running at fullscreen.
Best option is to run a few tests before you start