I have one small flat screen and one large CRT to spread my Poser program.  For the CRT, purchase a DVI/VGA converter for connection.  Once your set up is recognized, use the video properties to spread your desktop across two monitors.  When I activate Poser, I move my entire workspace to the smaller monitor and leave the preview window all by itself on the main monitor.  That way all my controls are one side and the scenes on the other.