size do not matter, only resolution does in the world of graphics cards
as for your 6790, what do you plan on doing with your new shiny monitor? the card will handle most games fine at medium settings at 1600X1200. but it all depends on what you're aiming for.
also, which websites/places do you shop at? we might as well find you a TV to go with this (btw, are you plugging your cable into your TV too? otherwise just get a nice large monitor