In "FolderOptions/File types" for "py" files in 
action "open" "Application used to perform action" 
reads: "C:\Python24\python.exe" "%1"

This results in such behaviour:

-----------
D:\temp>copy con test.py
import sys
print sys.version
print sys.argv[1]
^Z
        1 file(s) copied.

D:\temp>python.exe test.py hello
2.4a3 (#56, Sep  2 2004, 20:50:21) [MSC v.1310 32 bit 
(Intel)]
hello

D:\temp>test.py hello
2.4a3 (#56, Sep  2 2004, 20:50:21) [MSC v.1310 32 bit 
(Intel)]
Traceback (most recent call last):
  File "D:\temp\test.py", line 3, in ?
    print sys.argv[1]
IndexError: list index out of range
-----------

Python2.3 had this string for  "Application 
used...": "C:\Python24\python.exe" "%1" %*