Energetical evaluation of protein-protein interactions

Hi all,
 Does anyone know of a good protocol for evaluating the energetics of
 protein-protein interactions? More precisely, I would like to evaluate
 the individual residue-residue contributions in complex stabilisation.
 Also, does anyone have experience in doing this using CHARMM?
 Regards (and a late happy new year :-0 )
 Dominique Vlieghe, Ph.D.,
 Bioinformatics Core,
 Department for Molecular Biomedical Research (DMBR)
 VIB - Ghent University
 (new) 'Fiers-Schell-Van Montagu' building
 (new) Technologiepark 927
 (new) B-9052 Ghent (Zwijnaarde), Belgium
 (new) Tel : +32-(0)9-33-13.693
 (new) Fax : +32-(0)9-33-13.609
 (new) email:dominique.vlieghe!at!dmbr.ugent.be
 (new) www:http://www.dmbr.ugent.be/