I just found out I need to switch from mpich2 to openMPI for some code I'm running.  I noticed that it's available in an openSuSE repo (I'm using openSuSE 11.0 x86_64 on a TYAN 32-processor Opteron 8000 system), but when I was using mpich2 I seemed to have better luck compiling it from code.  This is the line I used:

# $ F77=/path/to/g95 F90=/path/to/g95 ./configure --prefix=/some/place/mpich2-install

But usually I left the "--prefix=" off and just let it install to it's default...  which is /usr/local/bin and that's nice because it's already in the PATH and very usable.  I guess my question is whether or not the defaults and configuration syntax have stayed the same in openMPI.  I also could use a "quickstart" guide for a non-programming user (e.g., I think I have to start a daemon before running parallelized programs).