HDMI cable connection problems?

I have a problem with my new HDMI cable. I have a Akai 52" plasma tv, a motorola hdtv compatable cable box powered by Shaw, and a Sony dvd home teathre system. I have 2 hdmi to hdmi cables, plenty of composite and component cables. What is the best connection to get the full experience? P.S. The sound only works through the sony dvd sound system.