Through work i'm starting to learn a little about video. There is loss in coax at every connection from the satellite reciever(yes cable Tv companies use satellites)and signal distribution offices. So they use amplifiers to boost the signal to make up for this loss. Newer Tv's and satellite/cable boxes come with amps inside them to help with this loss too. There is also different qualities in coax related to shielding and core size.
Short runs as in your house are very low on signal degredation as Mementh siad, but doesn't mean you can't have a bad connection which will interfere with performance be it video or internet service. The HDMI cable simular to the component cable seperate the different colors and signals being sent from the converter(cable/satellite box), DVD player, and AVR if capable. So, hopefully there isn't much loss between your house and your initial signal, and if there isn't then there is no problem once it hits your source of conversion.