Pycharm django project not using correct interpreter

Hi guys

I'm working with pycharm 3 pro on windows. I'm trying to set up a virtualenv to develop django  in.

I have my virualenv in /f/development3/tools/virtualenvs/. Its called "renv". I have a project in /f/PycharmProjects/ called "r1".

In pycharm I have set the interpreter to r1 to be the virtualenv "renv". However when I open a terminal and do:

    /f/PycharmProjects/r1 $ which pip
    /f/Python27/Scripts/pip

Obviously this is the wrong interpreter. Why is this happening and how can I fix this?

Thanks,

Bill