Does anyone know if iMovie 7.1 uses Core Video when playing video in the main window. In other words, would using a more powerful graphics card help iMovie play the video more smoothly? Or is it totally down to the CPU? We're talking an old AGP Powermac G5 here with a lowly FX5200 64mb and the video playback window is a little choppy (around 15 fps instead of 25).