We are using Sun Java 1.3.1 or 1.4 on Linux. We recommend using Java 1.4 unless your home directories are mounted over NFS, in which case Java 1.4 has an annoying but harmless bug.
http://java.sun.com/products/archive/j2se/1.3.1_02/jre/index.html http://java.sun.com/j2se/1.4/download.html
