Rapid Environment Editor (RapidEE) is one of those tools that should have been included with Windows by default. It displays the contents of the Windows environment variable as a tree, making it super-easy to examine, add or remove entries. It also verifies the validity of all paths and marks the invalid ones in red, so that the user can fix or remove those entries.
RapidEE is extremely useful if you do any kind of tweaking or programming on Windows. You will need to muck around adding or editing environment variables and RapidEE makes all of this a breeze. Start using RapidEE and I guarantee you that within a month you will not even remember the Windows dialog for viewing and modifying environment variables! ;-)
Tried with: Rapid Environment Editor 3.3