  A nested Fermi surface with nearly parallel orbit segments is found to yield
a singlet d-wave superconducting state at high temperatures for a restricted
range of the on-site Coulomb repulsion that avoids the competing spin density
wave instability. The computed superconducting transition temperature drops
dramatically as the nesting vector is decreased, in accord with recent
photo-emission data on the Bi2212 and Bi2201 cuprates.
