We examine the relative accuracy of a coupled Hartree-Fock/molecular mechanical (HF/MM) potential to a density functional/MM (DF/MM) coupled potential as well as other theoretical methods. GAUSSIAN 92 is used to model the quantum mechanical portion of the system, and AMBER 4.0 is used to represent the MM interactions as well as drive the energy minimization and molecular dynamics runs. Results from a bimolecular test case are presented which analyze the effects that basis set size and correlation play on the calculated results. Solvation free energies have also been calculated for a series of ions, and the results are compared to those given by experiment and other theoretical methods. Finally, the solution structure predicted by the HF/MM potential is examined through the calculation of radial distribution functions (RDFs) and coordination numbers.