YES! It is exactly what you assumed. 
 The default value is "C:\Python30\Python.exe", and  there is also another entry "path",its value is "C:\Python25\".
 
Does that mean I should not start python from the "Run" dialog box?
 
非常感谢您的回复！

> Subject: [issue4402] os.getenv('PATH') return different result between 2.5 and 3.0rc3
> To: zhaolu8@hotmail.com
> From: report@bugs.python.org
> Date: Tue, 25 Nov 2008 08:24:21 +0000
>
>
> Amaury Forgeot d'Arc <amauryfa@gmail.com> added the comment:
>
> Can you please check with the "regedit" application whether you have an
> entry for the key:
>
> "HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\Windows\CURRENTVERSION\App
> Paths\python.exe"
>
> (this key is used when you type "python" in the "Run" dialog box)
>
> What is its "(Default)" value?
> Is there an additional entry named "PATH"?
>
> (I presume that (Default)=C:\Python30\Python.exe, and PATH=C:\Python25\)
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue4402>
> _______________________________________

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