How can I run port-listening pgm on non-Admin account?

I have an application running on a W2003 server that is NOT a service,
therefore it starts running when someone logs in at the server. The
application listens on a specific port for client requests. It works fine,
but currently, I must log the server in using the Administrator account for
the clients to be able to access the program. I would like to be able to
log on with a non-Administrator account at the server. When I try this, the
clients can no longer see the port the app is listening on. Does someone
have an idea of what permission/privilige a non-admin account needs to make
this work?

Thanks,

Rob Kraft