My SMB1930N (1360x768@60Hz), 512MB GeForce 210 (nVidia) normally runs at 76 °C, and when i play games it reaches to 90 °C, especially when i play games like sniper ghost warrior so i think its pretty normal to have these temperatures on this video card, once it has a fan of its own as well. Moreso, i have four fans in my pc and on the other side the outside temperature is just 7 °C, so not to worry.
Thats not so good. Especially for a low end card.
Obviously something is wrong like the cooler isn't touching the GPU chip.
To answer the OP though, 57c isn't too bad for a GPU