  In the light of recent work which suggests that structure formation by cosmic
strings in a critical matter density universe requires large biases, we discuss
the effects of reducing the matter density. Using a full linear
Einstein-Boltzmann solver, we com pute the cold dark matter density field and
the microwave background anisotropies/polarization in a flat universe with a
non-zero cosmological constant. We find that universes with
$\Omega_{\Lambda}=0.7-0.8$ give a good fit to the shape of the observed ga laxy
distribution, albeit with a bias of around 2. This has interesting implications
for the anisotropy and polarization of the microwave background. Finally, we
discuss the effects of relaxing the assumption that the universe is flat.
