Is the AMD Phenom II X6 1055T good for gaming?

[Soleron]

No, an X4 965 or i5 750 for similar prices will be faster, because games don't use more than four threads well.

I would shift the CPU-GPU balance a little and get a more expensive GPU (5850 or GTX 470) and less expensive CPU (Core i3 dual or Phenom II X4 945).