Once you chose your driver and mudlib, you likely will want to keep up with advancements being made both in the mudlib and in the driver. Unlike other software you use, however, MudOS and Nightmare both provide you with their source code. Among other things, they allow you to modify that source code to suit your own needs. As you modify either the driver or mudlib, however, it becomes more and more difficult to merge changes made by either the MudOS or Nightmare developers in later releases.
You really should have no cause to modify the driver source. Because of this, upgrading to a newer driver is generally much easier than upgrading to a newer mudlib. Because there is no way of knowing exactly what changes you have made to your source, no document can tell you exactly how to upgrade your software. This document does however attempt to address the issues which you should keep in mind.
Whatever you are doing on the mudlib end, it is generally a very good idea to keep up with the latest MudOS developments. As major, stable releases are created, they are generally faster and more efficient than the older ones. They also tend to include newer technologies. How often you decide to upgrade, however, should depend heavily on how you use the driver.
The MudOS Home Page includes a description of the MudOS versioning strategy. Basically, if you like playing with bleeding edge technology and do not mind a driver prone to crashes, then you may want to play with the MudOS alpha releases (v#a# versions). Most people, however, will want to stick with the major releases, unless a minor release introduces a must have feature.
Your first task in upgrading your driver is to download the version you want from the MudOS FTP archives. Once you have downloaded it, you need to read the Changelog files to see what has changed. You need to specifically look for things called COMPAT BUSTERS. These are changes to the driver that affect the LPC language being used by the mudlib. They will let you know if you need to make any changes to your mudlib for it to run with the new version.
If you followed the Nightmare installation procedures, you saved a file called local_options. Once you have downloaded the new MudOS version and are ready to compile it, you should copy this local_options file into the MudOS source directory. All that is left is to follow the MudOS compile instructions and build the driver.
You are much more likely to have modified your mudlib code than driver code. For this reason, upgrading your mudlib wholesale is not recommended. Instead, it is recommended that you pick a full release of Nightmare (like Nightmare V) and integrate new features from later releases as you find them useful. For example, the first development after the release of Nightmare V will be a GUI administration tool. When an alpha or beta release with this feature is released, you can take the pieces from that Nightmare release and integrate them into your system.