The 560m is the rough equivelant to the GTS 450. As the GTS 450 averages around 40 FPS for most games at 1920 x 1080 at high/max settings, it should do fine. Playing the game in 3D will hurt your FPS. To answer your question about whether or not 3D is worth it, that depends on you. Do you really need to play a game in 3D? If you want to, then its worth it. If not, then its a waste.
HD movies will play very smoothly and you will have no issues on that set up.