Combined Backend Frontend
A backend/frontend combo machine is the most common setup for people wanting MythTV for HTPC applications. This type of installation is intended for use as a component in your home theatre. Like the frontend only, its not really necessary for a fully-featured desktop environment- a light window manager will suffice, and keep things simple. Since it is working in both backend and frontend capacities, the hardware for this type of machine will likely need to be more powerful than the previous setups.