I recently bought a house that came with a pre-plumbed plasma run for mounting the display over the fireplace. I'm quite happy with the job they did, but we bought it from a builder and I can't figure out what all the cables they ran are for. Hoping some here might have some ideas.

The plumb has two smurf tubes. The bottom tube has a pull string, so I can add whatever is needed. But the top tube has the following:
1) white RG6 cable with RF termination. This connects to house cable in the box, so I'm guessing the pre-wired it if you wanted to use the tuner on your plasma
2) A standard Cat 5e cable. There is also a cat5e cable in the box. I'm assuming this is house networking, and you could daisy chain/splice to the plasma if you wanted a network connection on your plasma
3) A big, thick black RG6 cable without termination on either end. I can't figure out why they ran this. I have Verizon FiOS, so I'm wondering if this extra cable is related to a DBS platform?

I was planning on pulling HDMI and RCA (for center channel) through the open tube. From what I've read, RG6 can't carry HD, so no advantage there. I've read some modulate HD over cat5e, but that seems to get expensive and more cluttered then just pullnig a HDMI cable since the plumb is already there.

Am I missing something to why they ran all these cables? Pulling HDMI isn't a big deal, but if I can use what's there then that is less effort...

Thanks!

HDMI is the best way to go assuming you get a Audio Video Receiver (AVR) that converts all A/V sources up to HDMI and other HDMI sources without long, expensive HDMI cables. I recommend the Denon AVR-2807, but their lower cost AVR's perform the conversion too.

Your center channel speaker will use stranded speaker wire.

The CAT5 can be used for a IR receiver to relay IR to your electronics using a IR hub and emitters. I recommend using a RF Remotes instead of relaying IR. RF is more dependable since you don't have to keep the remote pointed at the IR receiver when selecting a activity.