after installing django I tried
django-admin.py startproject mysite
django-admin.py startproject newsite
For anyone stumbling across this now, this problem is a result of Windows not obeying the #!C:\Path\To\Virtualenv\Scripts\Python.exe hashbang at the top of django-admin.py, and therefore running it with the wrong python.exe (evidently a virtualenv bug).
However, with virtualenv active, you can use the following command, which will result in the correct python being used, and everything being ok:
python C:\Path\To\Virtualenv\Scripts\django-admin.py startproject <project_name>