JBoss Messaging is bundled with EAP 5.1.2. If you get EAP 5.1.2 you get JBoss Messaging automatically. There is no standalone download for JBoss Messaging for EAP.
By the way with EAP 5.1.2 you have option to choose HornetQ as your messaging engine.
thanks for the reply,
I believe JBoss Messaging 1.4(JBoss EAP 5.1.2) has been around for a while and seems to be widely used than HornetQ (JBoss Messaging 2.x).
We are keen on stability than performance. Apart from performance, is there any reason why we should prefer HornetQ?
I found the foll. link, which has the details to convert a full JBoss 4.x Server to a Standalone JBoss Messaging 1.4 Server. I'll see if I can do something similar for JBoss 5.1.2.