Screenshare from the 10.8 server to the 10.5 server.
Make sure Remote Management / Screen Sharing is enabled on 10.5
From 10.8, choose 'Go to server' in Finde/Go menu and type
vnc://192.168.1.2 (whatever IP address of your server is)
If you are managing from outside the 10.5 server's LAN, be sure to open/map port 5900 in your router.
i got a way to open the Server Monitor App on 10.8.4
take the version from Server Admin Tool 10.7.5
then open the app with ctrl-klick > watch package content > go to the folder MacOS
here is the main application drag & drop this on the terminal or symply doubleklick
now make an alias to your desktop
it really works :-) i don't know why apple this has discontinued
hope this help all xserve users
i don't check with a 10.5 server, but it works from a 10.8 to a 10.7.5 server