In Windows 7 64-bit edition (x64), I installed the 64-bit version of Python 2.6. After installation, I had a lot of problems with trying to install packages via .exe installers.

I narrowed the problem down to the installers not looking in the "right" place for the Python installdir (or rather, not being able to find the Python 2.6 installation directory) from the registry. I concocted a simple .reg file to fix this:

 Windows Registry Editor Version 5.00
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python]
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore]
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6]
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\Help]
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\Help\Main Python Documentation]
 @="C:\\Python26\\Doc\\python265.chm"
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\InstallPath]
 @="C:\\Python26\\"
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\InstallPath\InstallGroup]
 @="Python 2.6"
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\Modules]
 
 [HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.6\PythonPath]
 @="C:\\Python26\\Lib;C:\\Python26\\DLLs;C:\\Python26\\Lib\\lib-tk"

After applying this .reg fix, things are working fine.

Download the fix file:
http://wi-fizzle.com/downloads/win7_python2.6_x64_reg_fix.reg