We are using a 400 watt inverter from West Marine, for exactly the same purpose as you described. It has been hard wired to our battery bank for 10 years without any problems. My thinking was a marine grade device should stand up to our needs.
I fitted it below the sink(the shortest run to our battery box) and use a short HD extension cord to power the Satellite box and DVD when of the grid. Its also a convenient locale to run the laptop. I use the lowest wattage that will supply the needed power to reduce battery drain. I'm not sure that is important but its worked well so far.