Running Scripts vs Interactive mode

[grobs456]

c:\dev\python>python HelloWorld.py
'python' is not recognized as an internal or external command,
operable program or batch file.

#I then tried this for a success!:

c:\dev\python>c:\python27\python.exe HelloWorld.py
Hello WOrld!

c:\dev\python>python HelloWorld.py
'python' is not recognized as an internal or external command,
operable program or batch file.


#I will utilize the advice regarding using IDLE but would like to
figure out how to do the above.
#Would this help me, per the tutorial?:
chmod +x HellowWorld.py

#I set my system environment variables to:

VARIABLE		VALUE
PYTHON_HOME		c:\python27\python.exe
PATH			...;%PYTHON_HOME%

#after also trying this:
VARIABLE		VALUE
PYTHON_HOME		c:\python27
PATH			...;%PYTHON_HOME%

#ALSO, I was confused by the following:
Add into each your *.py script and as the very last line this:
raw_input('Press any key to exit...')

#Thanks for all the assistance thus far.