You just need and adapter
You need an RF to S-video adapter. Every Radio Shack sells em, and there are probably 100 sites on the web as well. Search on google for S-video to RF..
Here is one link you can check outhttp://www.svideo.com/svideocoax.html
Just realize if you have a standard TV, you will only be able to run at 640x480 and maybe push it to 800x600. If you had an HDTV you could run at regular 1024x768 depending on your set.
My experience has been that DVD playback is marginally ok, but not nearly as good as if you had a dedicated DVD player, which you can pick up online for around 60 bucks. That is the way I would go if I were you.