Many of you have asked "can I use my cable TV wiring for Internet?" The original answer was, yes, but it costs about $200 to get "MOCA" adapters to make this work. While these will do exactly what you want, I have found a cheaper option ($14). Much cheaper. DirecTV created this networking standard for their receivers. The good news is, it works great for exactly what we want to do.
So, if you have a COAX cable (ie: cable TV cable) running to where your Internet router will be from either an old satellite dish or an un-used cable TV connection, we can buy these very inexpensive adapters to run Internet over at speeds beyond 100Mbps. All it needs is a cable line with nothing else on it (ie: no satellite, no Comcast, no off-air TV) and a power outlet at each end. As long as it is not used for anything else, two of these adapters will take our Internet from our dish to your living room without having to run any new wires or drill any new holes!
To buy a set of these, visit this Amazon.com link and get a pair. They look just like the setup above (minus the large spool of cable in the middle to test it).