panasonic th 42pz700u high definition plasma television

 I just pulled the trigger on a Panasonic TC-P55VT60 (awesome!) I have an older home theater system, nothing fancy, just a hodge podge of stuff. I'm new here and a beginner but I'm hoping someone can help me out   All of the audio is thru RCA and the video thru HDMI   Older Panasonic 42"...