Came here searching for properly detecting if running on 64bit windows, compiling all the above into something more concise.

Below you will find a function to test if running on 64bit windows, a function to get the 32bit Program Files folder, and a function to get the 64bit Program Files folder; all regardless of running 32bit or 64bit python. When running 32bit python, most things report as if 32bit when running on 64bit, even os.environ['PROGRAMFILES'].

import os

def Is64Windows():
    return 'PROGRAMFILES(X86)' in os.environ

def GetProgramFiles32():
    if Is64Windows():
        return os.environ['PROGRAMFILES(X86)']
    else:
        return os.environ['PROGRAMFILES']

def GetProgramFiles64():
    if Is64Windows():
        return os.environ['PROGRAMW6432']
    else:
        return None

Note: Yes, this is a bit hackish. All other methods that "should just work", do not work when running 32bit Python on 64bit Windows (at least for various 2.x versions I have tried).

Edits:
2011-09-07 - Added a note about why only this hackish method works properly.

Came here searching for properly detecting if running on 64bit windows, compiling all the above into something more concise.

Below you will find a function to test if running on 64bit windows, a function to get the 32bit Program Files folder, and a function to get the 64bit Program Files folder; all regardless of running 32bit or 64bit python. When running 32bit python, most things report as if 32bit when running on 64bit, even os.environ['PROGRAMFILES'].

import os

def Is64Windows():
    return 'PROGRAMFILES(X86)' in os.environ

def GetProgramFiles32():
    if Is64Windows():
        return os.environ['PROGRAMFILES(X86)']
    else:
        return os.environ['PROGRAMFILES']

def GetProgramFiles64():
    if Is64Windows():
        return os.environ['PROGRAMW6432']
    else:
        return None

Note: Yes, this is a bit hackish. All other methods that "should just work", do not work when running 32bit Python on 64bit Windows (at least for the various 2.x and 3.x versions I have tried).

Edits:
2011-09-07 - Added a note about why only this hackish method works properly.

Came here searching for properly detecting if running on 64bit windows, compiling all the above into something more concise.

Below you will find a function to test if running on 64bit windows, a function to get the 32bit Program Files folder, and a function to get the 64bit Program Files folder; all regardless of running 32bit or 64bit python. When running 32bit python, most things report as if 32bit when running on 64bit, even os.environ['PROGRAMFILES'].

import os

def Is64Windows():
    return 'PROGRAMFILES(X86)' in os.environ

def GetProgramFiles32():
    if Is64Windows():
        return os.environ['PROGRAMFILES(X86)']
    else:
        return os.environ['PROGRAMFILES']

def GetProgramFiles64():
    if Is64Windows():
        return os.environ['PROGRAMW6432']
    else:
        return None

Came here searching for properly detecting if running on 64bit windows, compiling all the above into something more concise.

Below you will find a function to test if running on 64bit windows, a function to get the 32bit Program Files folder, and a function to get the 64bit Program Files folder; all regardless of running 32bit or 64bit python. When running 32bit python, most things report as if 32bit when running on 64bit, even os.environ['PROGRAMFILES'].

import os

def Is64Windows():
    return 'PROGRAMFILES(X86)' in os.environ

def GetProgramFiles32():
    if Is64Windows():
        return os.environ['PROGRAMFILES(X86)']
    else:
        return os.environ['PROGRAMFILES']

def GetProgramFiles64():
    if Is64Windows():
        return os.environ['PROGRAMW6432']
    else:
        return None

Note: Yes, this is a bit hackish. All other methods that "should just work", do not work when running 32bit Python on 64bit Windows (at least for various 2.x versions I have tried).

Edits:
2011-09-07 - Added a note about why only this hackish method works properly.