You may want to investigate our SOA model. It may be better suited for your scenario, since it allows you to start up a service and then make multiple calls in to it without having to pay a start-up cost each time like you would if you were launching a new MPI app every couple seconds.
You'll find a bunch of resources on this on microsoft.com's technet & msdn libraries, here is one starting point http://www.microsoft.com/downloads/details.aspx?FamilyId=99742128-4C8C-4ADB-872E-C4099206C78D&displaylang=en