  Spin-dependent partial conductances are evaluated in a tight-binding
description of electron transport in the presence of spin-orbit (SO) couplings,
using transfer-matrix methods. As the magnitude of SO interactions increases,
the separation of spin-switching channels from non-spin-switching ones is
gradually erased. Spin-polarised incident beams are produced by including a
Zeeman-like term in the Hamiltonian. The exiting polarisation is shown to
exhibit a maximum as a function of the intensity of SO couplings. For moderate
site disorder, and both weak and strong SO interactions, no evidence is found
for a decay of exiting polarisation against increasing system length. With very
low site disorder and weak SO couplings a spin-filter effect takes place, as
polarisation {\em increases} with increasing system length.
