  We calculate the longitudinal and spin-Hall conductances in four-lead bridges
with Rashba - Dresselhaus spin-orbit interactions. Numerical results are
obtained both within Landauer-Buttiker formalism and by the direct evaluation
of the Kubo formula. The microscopic Hamiltonian is obtained in the
tight-binding approximation in terms of the neareast-neighbor hopping integral
$t$, the Rashba spin-orbit coupling $V_R$, the Dresselhaus spin-orbit coupling
$V_D$ and an Anderson-like, on-site disorder energy strength $W$. We reconfirm
that below a critical disorder threshold, the spin-Hall effect is present.
Further, we study the effect on the two conductivities of the Fermi energy,
Rashba/Dresselhaus coefficient ratio, and system size.
