  Hydrodynamical simulations are used in combination with the Press-Schechter
expression to simulate Sunyaev-Zel'dovich (SZ) galaxy cluster sky maps. These
are used to gauge the ability of future SZ observations to provide information
about the cosmological parameters H_0, Omega_M, and the gas fraction f_g in
clusters. This work concentrates on prospects for AMI, the Arcminute
MicroKelvin Imager, a new type of compact interferometric array currently
proposed in Cambridge. The expectations are contrasted with those for X-ray
missions, such as XMM, and the benefits of combining SZ and X-ray data are
highlighted.
