When the 30 days are over,
Orion and
jBoss are nice EJB servers to use.
Orion is a commercial all-in-one server (web, servlets, and EJBs), written in Java, with free developer's licenses. It will work fine on Win98 and isn't too much of a resource hog, comparatively speaking. The documentation is gradually getting there. There is some helpful tutorial material (which is worth reading no matter what app server you use), and the deployment tools provided mean you won't have to muck with XML configuration files for a while.
jBoss is an open source effort. Although I don't have nearly as much experience with it as I have with Orion, it seems very interesting from a technical point of view, and the development is pretty well managed. jBoss is my best bet to become the Apache of EJBs. Documentation is a sensitive point though. If you try it, be sure to download one of the versions that come with a servlet engine as jBoss is a pure EJB container.
Personally, when I first got into J2EE and EJBs, I found configuration and deployment the toughest nut to crack. Probably makes sense given that EJBs are an effort to shovel as much responsibility into the container as practical, and all that stuff has to be configured.
Have fun!
- Peter