The Microsoft JVM is an implementation of the
Java 1.1.4 API. If you attempt to use any class that was added to the api after that version your applet will not run in that VM. This includes Swing, java.util Collections, and a whole host of other very useful functionality like regex. Your best bet is to get your users used to downloading the java plugin. They don't have a problem installing Flash or Shockwave or Adobe Acrobat Reader (even worse) Comet Cursor or Bonzai Buddy, right?