title: Set up a python virtualenv with a specific version of Python
body: <p>I am trying to get started with Google App Engine. I have python 2.6 installed in my virtual environment which I wanted to use. But Google App Engine supports python2.5. So I want to set up another python virtual environment with python 2.5.</p>
  
  <p>Can you help me how to do exactly that?</p>