Using Python To Launch Python

[aha]

Hello All,
  I have a situation where I can count on a Python installation being
available on a system, but I can't count on it being a version of
Python needed by my application.  Since my application has it's own
version of Python installed with it how should I use the system Python
to launch the version of Python that launches my Application.  Yes,
this is a convoluted process, but not all Pythons are built the
same :)

Right now I am leaning towards using exec to start a new process, but
I thought I would check to see if anyone else has had the need to
perform a task similar to this one.

AHA