If you want to optimize the queuing or scheduling, you may use an optimization tool such as Lingo.
If you just want to simulate a speicific queuing model, it is very simple to write your own code using a script language such as Python or Matlab.
(The Matlab stateflow toolbox is used for state-machine simulation, for example of advanced queuing disciplines, but I think that is overkill in your case.)
I usually use omnet (http://www.omnetpp.org/) for similar simulation problems. It has queueing related example projects, which can be customized easily.
In my teaching (a master's-level simulation course in a Business Analytics curriculum), I use Simio www.simio.com. I highly recommend it for this purpose. This software has proved itself powerful, easy to learn and use, and vigorously supported.