I just installed Premiere CS3 (3.2) and Prospect HD (latest fix) on a new i7 system with ATI HD4870/1GB and 12 GB ram, working with Vista 64 SP1. When I work in a standard premiere project (monitor 1920x1200) I have perfect preview on my second monitor (1920x1080). When I use a cineform project, I have no preview. I have enabled overlay surface in the cineform settings and ATI catalyst I selected theater mode overlay in the avivo video settings with scale to full screen.

Any idea?

Make sure in Windows you have DE-selected "extend desktop onto this monitor." They need to be in clone mode or Overlay will not work with Cineform. Then in your ATI Catalyst control panel the settings you have sound correct.

Thanks a lot Adam,
but when I deselect extended desktop either in Vista, the second monitor is disabled - no preview. When I select clone mode in Vista or in Catalyst I have the exact copy (clone) of my primary monitor, but not a preview....

can it be Vista64 related?

I'm using Vista 64 and when I uncheck "extend" on the second monitor control panel I get a cloned/duplicate display in Windows of my desktop. It then works for full-screen output within Premiere/Prospect.

Don't know why your second monitor would vanish in Windows.