How to Hide and Lock Hard Disk Drives in "My Computer" window by GROUP POLICY

we can hide hard drives in my computer window by two ways... one way is command method and second method is group policy.. for this see below...
PROCEDURE:-
1.Type GPEDIT.MSC
2.Open the following sections: User Configuration->Administrative Templates->Windows Components->Windows Explorer.
3.Click Hide these specified drives in My Computer.
4.Click to select the Hide these specified drives in My Computer check box.
5.Click the appropriate option in the drop-down box.

NOTE:-

1.In this DIALOG BOX there is having only A,B,C,D DRIVES only.so we have change the C,D,E,F DRIVES as A,B,C,D...
2.In which method we hide the drives in that method only we have to unhide it.
3.close all my computer windows to take effectiveness.other wise u need to restart
4.when you are going to hide drives by command method... u just follow the screen shots... in that pictures, beware of caps and small letters. u have to type the letters as given in screen shorts...
5.keep patience when u r doing...
SCREEN SHOTS:-