You may also want to try GlassFish. Updated version of the Java EE 5 SDK was released toady. It is free. Sun's Application Server (9.0 Update 1 Patch 1) based on Project Glassfish is included in the SDK. It contains a performance bugfix that enables record-breaking price/performance on the application tier with SPECjAppServer result of 521.42 JOPS@Standard - see Scott's latest blog for all the details.