I just got a Samsung BD-F5700 with built in wifi. How do I connect it to my old Panasonic which has RCA plugs?

Solution
You will need an active HDMI to VGA/RCA adapter. Just a cable wont work as HDMI is a digital signal and vga & rca are analog.
These are $50 to over $100 the last time I checked.
Your money is better spent on a new tv IMO.