Changes the environment variables through registry :


- HKEY_LOCAL_MACHINE
\CurrentControlSet\Control\Session Manager
\Environment


You see the same entries displayed here like as you navigate to
Contorl Panel/System/Special and click on
Environment Variables.

Note:

Variables in form like %PATH% must be stored as a
REG_EXPAND_SZ value.

If you are not confident with the registry,
please use the common way mentioned above.