The colored "RCA" cables you have (Yellow is video, Red and White are audio Left and Right) are ok to use, but you won't get HD. The picture will be reduced on the newer tv's. You can get a cable to go from the colors to a HDMI (that's the flat input) however it still won't be any better, just easier to hook up. What are the colored wires coming from? If it's a dvd player, check to see if there's a HDMI connection on the back. If so, ditch the colored wires and get a HDMI cable. It's "all in one", video and audio. If not, can you replace the dvd player with a newer model? It's best to go HDMI all the way through.
If you have any questions, pm me and I'll try and help you figure it all out.
2013 Itasca Sunova 30A
2006 Crownline 250cr
2012 Ram Laramie Longhorn