argv[0] and __file__ inconsistency

[Hai Vu]

I currently use ActivePython 2.5.1. Consider the following code which
I saved as cmdline.py:
    import sys
    print sys.argv[0]
If I invoke this code as 'python cmdline.py', then the output is:
    cmdline.py
If I invoke it as 'cmdline.py', then the output is:
    C:\Users\hai\src\python\cmdline.py

The same happens for __file__. My question: do you have any
suggestions for a more consistent way to figure out the full path of
your script?