I just wrote a System-wide Environment Editor for Windows (2k/xp).
It serves me as a replacement for the built-in one, which is a bit ugly when comes to editing specific variables as PATH, PATHEXT, INCLUDE, etc.
http://homepage.mac.com/malkia/swee32.zip - (285kb, source+exe)
comments to firstname.lastname@example.org
I’ve did slight change to Juce-1.9, and the header is included.