What protocol using wcf?

Question

My silverlight application is using basicHttpBinding protocol.

Now I need to implement a new feature that is notify clients. The binding used for this feature is the DuplexHttpBinding? Can I use both together?

This application will be installed on a provider where several clients can use it and can also be installed on an intranet. So I have a better performance, what do you recommend binding to each case?

Thank you

Teles