  We analyze the spectral and transport properties of ballistic quasi
one-dimensional systems in the presence of spin-orbit coupling and in-plane
agnetic fields. Our results demonstrate that Rashba precession and intersubband
coupling must be treated on equal footing for wavevectors near the magnetic
field induced gaps. We find that intersubband coupling limits the occurrence of
negative effective masses at the gap edges and modifies the linear conductance
curves in the strong coupling limit. The effect of the magnetic field on the
spin textured orientation of the wire magnetization is discussed.
