yes gauge matters, majority of gauge depends on whether you're making in-wall runs or not, but can affect regular runs as well. Typically you want to stay under 28AWG for an HDMI cable. As stated already, monoprice.com is the only place people need to be looking at cables. The rest is hype, don't be a douche and buy into Monster's bullshit. I managed a car stereo install bay in high school, worked at one in college which I was the master fabricator and installed several competition systems edit:**screw my resume', just know I have an extensive audio/video background*** and as long as you understand ohm's, power, noise and all you'll be fine with most cables. Buy good cable to start with, good connectors, make your own shit. I make my own guitar cables, speaker cables (monoprice cable/Nakamichi banana), RCA cable (composite/component), ethernet cable..etc..can't make HDMI cables..lol

The cables you want are 1.3a; b is slowly coming out, but it's about as much over hyped as CAT6. To attain 1.3a transfer rates all your components must support it. Kinda like USB 2.0. The advice given thus far is on par. Runs that go over 30-35 ft could benefit with an additional power replicator, which monoprice also sells though. Usually your looking at ~50' before you need a replicator. I doubt anyone here will be running that long of a cable.