Yes, you need MQ in house. You'll need a config that includes sender and receiver channels on both sides. Having said that, you might consider Websphere 5 in this case as it includes a light version of MQ that should suffice for your purpose.
...if you use Websphere 5 (or SonicMQ) you can avoid a full blown install of MQ.
Websphere has definitely improved from the really buggy days of the 3.x releases. Version 5, in particular, has some interesting clustering functionality that I'm testing right now. It allows an instance to ride over multiple physical machines (running the same or different OSes) during runtime.