Start --> run --> [type] regedit [press ok] -->

traverse to--> HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Directory\shell\

Right click on "shell" and select "New --> key" and name it as "decompile"

Right click on "decompile" and select "New --> key" and name it as "Command"

Click on "Command" and modify the data in default to

jad -r -d "%1%_decompiled"  -s .java  "%1%\**\*.class"

You will see the "decompile " item in the menu when you right click your folders.

This will decompile the contents of the folder to another folder with name %Directory_name%_decompiled

Enjoy