How do I tell python to use a different version of django in apache2/mod_wsgi environment?

Question

I have been given a laptop to use. And the wrong version of django is being used inside a django app deployed on apache2/mod_wsgi.

The app requires Django 1.3. But it currently is using a django runtime of 1.2.3

I ran

$ python -c "from distutils.sysconfig import get_python_lib; 
    print get_python_lib()"
/usr/lib/python2.6/dist-packages

But django seems to be installed in

/usr/local/lib/python2.6/dist-packages

And there's also this other directory:

/usr/lib/pymodules/python2.6

And running this prints out 1.2.3

python -c 'import django; print django.VERSION;'

I'm a newbie to python/django.

1. In the first place, how are the directories searched and in what order & how are they configured?
2. The error page on the browser printed out a PYTHON_PATH. How do I modify that ?