Quantum chemical fully ab initio conformational calculations was performed for the weakly bound van der Waals N2...H2 and N2...He dimers in the framework of the supermolecule approach. The counterpoise-corrected interaction energies were computed through fourth order MBPT using basis sets constructed to give accurate values for the electric moments, polarizabilities and dispersion energy contributions. The best size-to- performance ratio basis set found in the present study, predicts the T-shaped structure to be the most stable configuration for N2...He, with a well depth D(e) of 2.68 meV at a minimum distance R(e) of 3.44Å, in close agreement with calculations performed with larger basis sets. The relative stability of the configurations studied for N2...H2 were: collinear structure > parallel structure > T-shaped structures. The collinear structure represent the most stable configuration, with a D(e) value of 8.35 meV at a equilibrium distance R(e) of 7.60a0.