I have installation of python 2.7 and 3.3 side by side (C:\\Python27 and C:\\Python33). I am now trying to install virtualenv.
Python2.7 is my default interpreter. When
I'd imagine your environment variables are set up to use the python2.7 environment variable for python and the path to the python3.3 pip for that, you either need to adjust those or use the full paths when using the tool as you require.
python
pip