FYI

If you installed anaconda it's going to want you to use it's package manager for virtualenv (you'll have noticed this if you've followed the repo notes):

C:\Users\Laura>pip install virtualenv

WARNING: using virtualenv with conda is untested and not recommended.
    We suggest using the conda command to create environments instead.
    For more information about creating conda environments, please see:
        http://docs.continuum.io/conda/examples/create.html

Proceed (y/n)?

C:\Users\Laura>conda env
usage: conda-env-script.py [-h]
                           {attach,create,export,list,remove,upload,update}
                           ...

positional arguments:
  {attach,create,export,list,remove,upload,update}
    attach              Embeds information describing your conda environment
                        into the notebook metadata
    create              Create an environment based on an environment file
    export              Export a given environment
    list                List the Conda environments
    remove              Remove an environment
    upload              Upload an environment to anaconda.org
    update              Update the current environment based on environment
                        file

optional arguments:
  -h, --help            Show this help message and exit.

C:\Users\Laura>conda install virtualenv
Fetching package metadata: ....
Solving package specifications: ....................
Package plan for installation in environment C:\Users\Laura\Anaconda2: