I'm trying to install, on my 18 processor opteron cluster, software (NAMD) which uses MPI, but I've encountered some problems which I'm afraid are related to my lack of understanding of MPI. This cluster was purchased as "turnkey," so I assume the MPI implementation is automatic, but is there anything which is software dependent? Does each machine need a copy of the software, or does MPI know how to share without multiple copies? This question almost sounds like it might belong in the NAMD list, but I'm hoping someone can give a quick and dirty MPI lesson so I know for what to look.

Thanks for anyone with time to help address this need. A few hours with google have failed me.