I have v2.7, v3.2, and v3.3 installed on a Win7 64-bit machine and the exact same setup on a Win7 32-bit machine.

The 32-bit works OK.  The 64-bit machine had this argv problem, too!  (I tried installing either Win32/Win64 version, no difference!)

Adding %* fixed the argv problem, but I noticed there was one more.  The wrong version was called.

To sum it up, I had to change only the key
HKEY_CLASSES_ROOT/py_auto_file/shell/open/command

from:

c:\Python32\Python32.exe "%1" %*

to:

c:\Python33\Python33.exe "%1" %*

or to:

c:\windows\py.exe "%1" %*

(for auto-detection, both worked)