In the details pane, right-click the group you want to
administer, and then click Properties.
Click the UNIX Attributes tab.
In the GID (Group ID) box, type the new group identifier
(GID) for the group.
To save the changes and keep the dialog box open, click
Apply. To save the changes and close the dialog box,
click OK.
Notes
To open Active Directory Users and Computers, click
Start, point to Programs, point to Administrative
Tools, and then click Active Directory Users and
Computers.
There is no command-line method for this procedure.