If you are managing a server running Mac OS X Server 10.2, you don't have to stick with the 10.2 Admin tools. Although Apple doesn't mention it, the 10.3 Admin tools will (for the most part) allow you to manage older servers. Workgroup Manager in particular is significantly improved over its 10.2 incarnation. Server Admin 10.3 will start and stop services on 10.2 Server, but to configure settings, you will still need to use Server Settings 10.2.
The 10.3 Admin tools do require 10.3 on the client side. They can be downloaded for free from Apple's site.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040826163218586