From LedHed's Wiki
With Remote Registry Enabled on the target PC you can change the Computers description to something useful.
Open Regedit and click "File" then "Connect Network Registry"
In the dialog window put the PC's IP address or Hostname and click "OK".
The target PC's Registry should now be accessible from the Tree in the left pane.
Navigate to:
HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
Edit the "srvcomment" key to what ever description you like.
References
http://martums.blogspot.com/2006/09/windows-computer-comment-in-registry.html