Install python 2 and 3 in the "wrong" order

[Nagy László Zsolt]

I have Python 3.3 installed on my Windows 7 x64 box. Today I had to 
install Python 2.7 for an older app of mine.

Here is my problem: although "#!/usr/bin/env python3" is given in the 
file and "py -3" program works fine, apparently the installation of 
python 2 simply has overwritten my settings (e.g. assignment *.py files 
to py.exe).

Question: is there a way to fix this? Or do I have to reinstall Python 3 
from scratch? (It would be a pity, I have tons of third party modules 
installed for it...)

Thanks

    Laszlo