Running 2 instances of symfony on one machine

Are you still using both symfony 1.0.x and symfony 1.2.x
We’ve figured out another one solution which you can use to keep both branches on same Windows machine.

So you can keep symfony 1.0.x branch configured on Windows and you can run portable Ubuntu:

Portable Ubuntu Runs Ubuntu Inside Windows

and install symfony 1.2.x on it.
Ubuntu approach has really huge advantage though: you can keep your symfony configured and ready on USB drive and you can use it wherever you need (e.g. you can take it into pocket for demonstration).