Well the actual size of the screen dosn't matter, its the resolution (height and width measured in pixels) that matters.
Most nice TVs today are 1920x1080p, I assume thats what your using.
That said, running Google earth at 1080p isnt gonna be too hard for a computer, but the component doing the work is gonna be the graphics card.
Just stay away from anything that says "Intel HD graphics" or "Onboarrd graphics" to make sure you get an actual card and you should be fine.
Sounds like a cool setup, good luck!