[ddouglass]

Just to make sure first did you activate the second display and set it as Extended in the Display tool in the Control Panel?
I don't think you can go directly from a VGA out to a TV-RCA input. It is the wrong type of signal. You are going to need a converter box in between to change the VGA signal to TV output.
I looked at the specs for the 1545s at Dell and all of them had an Intel Graphics card with no option for upgrading from it. I also checked for the outputs and it looks like the VGA output is all you have so as I said above you will need a converter box. A conversion cable like that isn't going to work according to some of the guys on the forum who use this kind of set up.
I just got a new Dell desktop (can't remember the model right now) and the ATI card in mine has DVI, VGA and HDMI outputs. So in my case I can use the HDMI out but will need a TV that uses it so none of the older tube TVs will work on it without some type of conversion box.