Google App Engine

I've recently been messing around with the Windows version of the Google App Engine again. I successfully built & ran the helloworld application after I encountered a small error. On this page you are told to enter the following in a Command-Prompt...

google_appengine/dev_appserver.py helloworld/

However after entering it, I recieved the following error...

'google_appengine' is not recognized as an internal or external command, operable program or batch file.

This error can be solved simple by omitting the beginning of the earlier command & typing in the following.

dev_appserver.py helloworld/