You can download Pybio here. You will also need Python. Remember to choose to install Tk bindings for Python (included in standard python distribution) as Pybio uses them to draw GUI. I use Python 2.2.3, so Pybio is thoroughly tested under this version of interpreter. It should run (actually it has to, but you never know ;) on Python version 2.3. Older versions might not work. Please contact me in such case, so I will be able to make my program more compatible (although upgrade to newer Python version is recommended ;)
To Windows users - source available under above location will run on any Python capable system. Standalone executables will also be made available soon, so Python installation will not be required to run Pybio under Windows.