Well I'm happy to report that between the ATI driver and the adjustments to the screen outputs, and other tweeks to the SDI card drivers (turning off desktop preview, etc) I am getting smooth playback of two layers, one at 30fps and the 2nd at 28-30fps.
Graphics performance at the HUD is reported at 100% with the occasional small drop that comes back up to 100% before I can read what it is.
Are there other elements I could watch out for too boost performance at all?
Laura