You can edit CFG files in any text editor. I usually use Notepad. I suggest associating CFG files with Notepad.
Copied from my Working with Windows tute.Associating File Extensions
Associating CFG files with Notepad will make editing them much easier.
Right-click on the file icon & select "Open With" from the drop-down menu.
Choose Notepad from the list & check the "Always open files of this type with this program" box.
Click OK to open the file.
Next time you wish to edit any CFG file, a double-click on the icon will open the file in Notepad.
Other file extensions can be associated with commonly used programs & utilities in the same way.