  We compare predictions of the mean-field theory of superconductivity for
nearly antiferromagnetic and nearly ferromagnetic metals in two dimensions. The
calculations are based on a parametrization of the effective interaction
arising from the exchange of magnetic fluctuations. The Eliashberg equations
for the transition temperature are solved including the full momentum
dependence of the self-energy. The results show that for comparable parameters
d-wave singlet pairing in nearly antiferromagnetic metals is generally much
stronger than p-wave triplet pairing in nearly ferromagnetic metals in quasi
two dimensions. The relevance to the layered materials, and in particular
Sr2RuO4 that exhibits p-wave triplet pairing, is discussed.
