I want to hook up my old SONY WEGA Projection TV to Chromecast so I can run itunes downloads and Netflex movie downloads on the HDTV. I have been told that I can connect the Chromecast to an "HDMI to Composite Cable (yellow,red,white) Converter Adapter" and then connect my TV with composite cables to they HDMI/AV adapter. Will that work.

I have a Chromecast on a new TV. My understanding that the whole idea of paying $35 for it is so that it's wireless - no extra benefit. I had the same results before, with an HDMI cable from my computer to me TV, for less money.

Here is a pretty good article,

chromecast TV has no HDMI port RCA | vimalsuresh

My point is that it's pointless to buy a Chromecast when you need a cable anyway.

Not in this case since it takes a TV with composite inputs and makes it a wireless receiver of sorts. Quite a neat trick fro an old TV.