I second Jay on this; the XDCAM Viewer especially shines when playing back 24/25/30p material - the infamous "progressive stuttering" is virtually non-existent using it, which is a proof of the real quality of the Cinealta line of cameras in this mode.
That's a very good viewer Jay! First one I've used that permits my underpowered laptop to have smooth sharp playback with in-sync sound. Check the option box for the alterntative renderer.