Bluff Titler & Direct X 11
This is not a cheap system, (about £50 for the upgrade and one set of templates), and I write to warn others who may fall into the same trap.
I use CS5 for editing, generally in HD, and have found my system copes very satisfactorily. However the latest version, (13), of the Bluff Titler software requires a Graphics Card which has "DirectX 11" functionality. My Nvidia Ge Force 9600 GT card does not posses such capability.
The Bluff Titler people recommend the nVidia GTX 960 card, costing about £200. This without worrying about any extra power requirements.