import error due to failure to link to libraries

Dear psycopg community,
have tried many ways of installing psycopg2 after having installed
PostgreSQL using the one-click installer, but anyway I try confronts
me with the same import error in python: ImportError: dlopen(/Library/
Python/2.5/site-packages/psycopg2/_psycopg.so, 2): Library not loaded:
libpq.5.dylib Referenced from: /Library/Python/2.5/site-packages/
psycopg2/_psycopg.so Reason: image not found

I am on Mac OS X 10.5.8. I am using Python 2.5. I installed PostgreSQL
from the installer (I did not port it) and it installed in /Library).
I added /Library/PostgreSQL/9.1/bin to the setup.cfg of the source
psycopg2, as instructed in the INSTALL file and everywhere on the
internet and then ran sudo python setup.py build and then sudo python
setup.py install. I also tried exporting /Library/PostgreSQL/9.1/bin
to my path instead and running sudo pip install psycopg2. But the
exact same problem occurred in all of these scenarii. I would greatly
appreciate some help with this.

Best Marion