  We consider a Schroedinger operator with random potential distributed
according to a Poisson process. We show that expectations of matrix elements of
the resolvent as well as the density of states can be approximated to arbitrary
precision in powers of the coupling constant. The expansion coefficients are
given in terms of expectations obtained by Neumann expanding the potential
around the free Laplacian. One can control these expansion coefficients in the
infinite volume limit. We show that for this limit the boundary value as the
spectral parameter approaches the real axis exists as well. Our results are
valid for arbitrary strength of the disorder parameter, including the small
disorder regime.
