digital set-top-box S-Video cable connections

I just got a television that has rear S-video cable options and I am considering buying a set-top-box for digital tv - (that's what we call them in australia)
my first one in a different room is connected via standard RCA cables into the AV - red-yellow-white but my question is should I fork out some cash for a good set of S-Video cables to connect the new STB ?
would it be a slight picture quality improvement?
I do understand I still need to connect the left/right audio separately.
any advice? is S-video worth it?