Windows – Different PATH environment variable for 32bit and 64bit Windows – is it possible

Your path is the concatenation of the system path followed by the user path. Additionally, system environment variables may not contain references to user environment variables, and any such references will not be expanded. To get the desired result, insert the reference to %JAVA_HOME% in the user environment variable PATH, or create such a variable if it doesn't already exist.

Perhaps a simplified example will make this clearer. Suppose the SYSTEM environment is

ProgramFiles = C:\Program Files
SystemRoot = C:\WINDOWS
PATH = %SystemRoot%\SYSTEM32

and the User JSmith's environment is

JAVA_HOME = %ProgramFiles%\Java\bin
USERPROFILE = C:\USERS\JSmith
PATH = %JAVA_HOME%\bin;%USERPROFILE%\bin

then the resulting path would be

C:\WINDOWS\SYSTEM32;C:\Program Files\Java\bin;C:\Users\JSmith\bin

as desired.

Put the 32bit .DLLs into the \Windows\SysWOW64 directory and the 64bit DLLs into the \Windows\system32 directory.

EDIT:

Maybe this helps:

This is just an intelligent guess, but following some investigation I believe I've found the problem:

If the definition of an environment variable var1 contains another environment variable var2 and the name of var1 is alphabetically less than the name of var2 (i.e. strcmp(var1, var2) < 0), then var2 won't get expanded. This seems to be because when Windows first sets up the environment variables, they are created in alphabetical order, so var2 does not exist until after var1 has already been created (and so the expansion can't be done).

I believe this is a limitation in Windows. Really some sort of dependency check between the variables should be carried out so that they are created in the correct order. Fortunately, there is a workaround.

1) Enable 'delayed variable expansion' in the registry (see http://batcheero.blogspot.com/2007/06/how-to-enabledelayedexpansion.html)

2) Change the '%' signs around var2 to '!', e.g. "%var2%" becomes "!var2!"

I've done some limited testing on Windows 7 and this appears to fix the problem.

It's from here: http://social.answers.microsoft.com/Forums/en-US/vistainstall/thread/48b23109-9fbc-47c5-a5d1-465773f94704