I know about the %USERPROFILE% system defined environment variable on Windows XP (and Vista and Windows 7). Is there a system defined environment variable pointing to the location of the "My Documents" directory? On XP by default it's %USERPROFILE%\My Documents and on Win 7 it's %USERPROFILE%\Documents. I just wanted to avoid having to test for the OS version in a Powershell script if I can avoid it.
On my default-installation XP system, there is no environment variable for that. You can list all variables with the "set" command ( no parameters ) in the command line. So probably you have to do a test.
If you don't want to test for the OS version, you can simply check whether "Documents" exists and if not then try "My Documents" or vice versa. This isn't perfect however, because s/o could have a "Documents" folder on his XP machine.
Btw: my system is German, so the folder is called "Dokumente". You might need to take that into account.
The path to that folder is stored in
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
under Personal. You need registry access, though.
Source: Microsoft