The H/K is a superior receiver. There is no way I would purchase a Yamaha 2400 over it. I just bought a 630, and based on my experience over the last two weeks, I wouldnt trade it for the Yamaha, and the 7200 is more powerful than that.
I suppose the confusion is why you would have cable, but no cable box. You would get that from the cable company, and I believe you would need one. You could then run the video and audio signal (how depends on the box and whether it is a digital or analog signal, and what connectors the box has)...
Not to hijack this thread, but I was about to post something similar. Perhaps the reply would be beneficial to Chip as well. I have a HK 630 on order and am looking to get my first set of surrounds, and I will be using them 60/40 classical music/HT. Now I hear that particular speakers work...