I have seen too many folks get HDTV and then use some archaic cabling to connect video sources.
The proper way to connect a HDTV to get the best performance that you paid for is to connect to your HD source ( Cable, Satellite HD programming) or Blu Ray player using HDMI. HDMI is a single cable that carries all digital video and audio. So you only need 1 cable.
Using svideo, composite cabling will degrade picture quality.
In my setup, I have:
Cable Digital Settop box with the HD package
Blu Ray Player
Xbox 360 for gaming.
Since I have several HD sources, I connect it to my HDTV thru a HDMI switch which allows me to select between the different sources.