refresh windows variables without reboot

In Windows2003
    1, In a command prompt type: runas /user:yourusername@yourdomain cmd
    2, It will open up a new cmd prompt and type: taskkill /f /im explorer.exe
    3, Then type: c:\WINDOWS\explorer.exe
   
refers:  

http://serverfault.com/questions/8855/how-do-you-add-a-windows-environment-variable-without-rebooting
    http://stackoverflow.com/questions/171588/is-there-a-command-to-refresh-environment-variables-from-the-command-prompt-in-w