Every option you ever wanted to set for Windows Messenger v5 - Group Policies!!

You need to copy a file from the Live Comm. Server CD-ROM
(Setup\i386\rtcclient.adm) to the c:\windows\inf folder on each client
computer.

Then select Start > Run and type in gpedit.msc to start the Group
Policy editor. Select Computer Configuration > Administrative
Templates and then Add/Remove Templates... from the Action menu.

Click the Add... button in the dialog that appears and then choose
rtcclient.adm from the file dialog that appears.

Once the file has loaded you should have a new node under
Administrative Templates called Windows Messenger Policy Settings with
lots of juicy options split across 3 categories!

Cheers,
Gary.