  We study numerically the ground-state properties of the repulsive Hubbard
model for spin-1/2 electrons on two-dimensional lattices with disordered
on-site energies. The projector quantum Monte Carlo method is used to obtain
very accurate values of the ground-state charge density distributions with
$N_p$ and $N_p+1$ particles. The difference in these charge densities allows us
to study the localization properties of an added particle. The results obtained
at quarter-filling on finite clusters show that the Hubbard repulsion has a
strong delocalizing effect on the electrons in disordered 2D lattices. However,
numerical restrictions do not allow us to reach a definite conclusion about the
existence of a metal-insulator transition in the thermodynamic limit in
two-dimensions.
