Your last command uses system-wide python in C:\Python27
that is available using %PATH% variable.
Just change your last command to use
C:\env>.\Scripts\python pyramid_hello.py
or from any directory containing your scripts use an absolute path to run it with your %VENV% python interpreter.
c:\scripts>%VENV%\Scripts\python pyramid_hello.py
May be you will find it more convenient to activate/deactivate your virtualenv. Experienced users tend to have it explicit and the pyramid docs usually do not use virtualenv activation. For pyramid beginners it may be a good idea for their first steps. Just a matter of taste.