  We consider a one-dimensional mesoscopic Hubbard ring with and without
disorder and compute charge and spin stiffness as a measure of the permanent
currents. For finite disorder we identify critical disorder strength beyond
which the charge currents in a system with repulsive interactions are {\em
larger} than those for a free system. The spin currents in the disordered
repulsive Hubbard model are enhanced only for small $U$, where the magnetic
state of the system corresponds to a charge density wave pinned to the
impurities. For large $U$, the state of the system corresponds to localized
isolated spins and the spin currents are found to be suppressed. For the
attractive Hubbard model we find that the charge currents are always suppressed
compared to the free system at all length scales.
