JMS implamentations

[Mark Herschberg]

I am looking for a free JMS implamentation. The system doesn't ahve to be very good. The only real constraint is that we can have 200-300 people "trade stocks" at once. Basically, we'll have people submit buy/sell offers, and those offers will then apprear on the "tickers" (we're actually using order books) of the other users. I should imagine this isn't too high a load. The hardware will be a decent (meaning average) server.
1) Is the reference implamentation from Sun good enough?
2) What about JBoss?
3) What *free* JMS implamentation do you recommend and why?
4) Can I use one EJB implamentation and a different JMS implamentation?
--Mark

[Vladimir Ergovic]

Some free JMS server beside JBoss is
http://openjms.sourceforge.net/
there was open3.com jms server but now it comercial.
I think for that purpuse Jboss would be fine.