Well, to be fair, that's not entirely true....
I'll explain it this way... With something like component cables, there is a quality difference between brands. Since the signal is analogue, there is the possibility of it degrading along the way. If the cable isn't shielded, electrical interference can distort the signal, and it won't be "perfect" when it comes out the other end into your TV. Most of the time, you won't even notice this degradation, but in some cases, specifically with long cables (where it has longer time in transit to break down), you might notice a loss in quality. Getting properly shielded cables should take care of this, whether they are mid-range or top-of-the-line brands.
With HDMI, the story is different. The signal sent is digital, it's all 1s and 0s. So if something goes wrong along the way, it jsut won't work at all. There's no break down of the end result.... it'll either work, or it won't. Therefore, there is absolutely no point in shelling out over $100 at Best Buy (those ****ers) for an HDMI cable when the job can be done just as well by a $6 one from the website above. It's the biggest scam going... people don't know any better so when they've just bought a high end tv and surround sound system, of course they're gonna feel pressured into getting the "good" HDMI cable. It's nonsense.
As a footnote, one factor that does matter with HDMI is length. If you get something too long, it may not work as reliably as a shorter cable.
/thread hijack. Sorry Ivan