In tip 2299, we ran the themes tool.
Windows 2000 uses a .theme extension to define a theme.
Previous versions of Windows used .the or .thm files. You may be able to use these older themes by renaming the file to a .theme extension.
Some older themes rely on the existence of the %THEMESDIR% environment variable to find the location of the theme file.
Even after you define the %THEMESDIR% environment variable, you may need to edit a theme in NOTEPAD to determine the folder structure that it requires.