  Using the four-terminal Landauer-B\"{u}ttiker formula and Green's function
approach, we calculate numerically the spin-Hall conductance in a
two-dimensional junction system with the Rashba spin-orbit (SO) coupling and
disorder. We find that the spin-Hall conductance can be much greater or smaller
than the universal value $e/8\pi$, depending on the magnitude of the SO
coupling, the electron Fermi energy and the disorder strength. The spin-Hall
conductance does not vanish with increasing sample size for a wide range of
disorder strength. Our numerical calculation reveals that a nonzero SO coupling
can induce electron delocalization for disorder strength smaller than a
critical value, and the nonvanishing spin-Hall effect appears mainly in the
metallic regime.
