Using the single chain mean field (SCMF) theory we investigate the effect of soluble polymer chains on the surface tension between a solid surface and liquid films. We find that end-grafted chains (brush) strongly reduce the surface tension between a liquid and an incompatible solid. This reduction is insensitive to the type and strength of monomer-solid interactions. Free chains reduce the surface tension between the liquid and the solid only if the monomer-solid interaction is attractive. Combining free and densely end-grafted chains is found to inhibit wetting, due to an inherent incompatibility between the grafted polymer brush and the free chain solution. Combining free and moderately end-grafted chains is found to enhance wetting if the monomer-surface interactions are attractive. These predictions are in good agreement with the experiments of Yerushalmi-Rozen et al.