Many differential equations of Dynamics (i.e. Celestial Mechanics, Molecular Dynamics, and so on) one can reduce to polynomial form, i.e. to system of differential equations with polynomial (in unknowns) right-hand sides. First, we show how to obtain such polynomial system fifth, fourth and third degree for classical Newtonian N-body problem. After that, we present comparative data (the relative errors of the coordinates and velocities of bodies and CPU times) for numerical integration of these systems on the interval [0, T] using two different Taylor series method algorithms.