An HDMI cable is transporting a stream of zeros and ones. Unlike analog cable which have impedence and loss issues, a digital cable either works or it doesnt. Monster Cables and other high end cables are snake oil, they work absolutely no better or worse than the cheapest freebie HDMI cable. When I think of all of the millions of dollars these companies make from consumers ignorance, yeesh, what a business.
Same with FireWire, USB, SDI, SPDIF or any other digital connection, they either work or they don't, there is no such thing as "higher quality" digital in these connections.