While the GTX 550 is below the 460 in specs/benchmarks, it will still run TOR perfectly fine I'm sure. You don't need a high end machine to play this game. You can check the system requirements here: http://www.starwarsmmo.net/system-requirements/
Can you link the thread where you were told that card wouldn't be good enough? Since I haven't played the game on my own system I don't know how high the graphics settings would go but just based on the minimum requirements I have to believe you could play on max.