In the framework of the Constrained MSSM we derive the most probable ranges
of the diffuse gamma radiation flux from the direction of the Galactic center
and of the positron flux from the Galactic halo due to neutralino dark matter
annihilation. We find that, for a given halo model, and assuming flat priors,
the 68% probability range of the integrated gamma-ray flux spans about one
order of magnitude, while the 95% probability range can be much larger and
extend over four orders of magnitude (even exceeding five for a tiny region at
small neutralino mass). The detectability of the signal by GLAST depending
primarily on the cuspiness of the halo profile. The positron flux, on the other
hand, appears to be too small to be detectable by PAMELA, unless the boost
factor is at least of order ten and/or the halo profile is extremely cuspy. We
also briefly discuss the sensitivity of our results to the choice of priors.