Unfortunately, the audio debacle spilled over to the digital world.
JJ, here's the story technically.
At the frequencies necessary for proper digital communication, we resort to transmission line theory, which, for audio made no sense at all given the cable lengths.
Transmission lines require termination in a load which matches the characteristic impedance of the line, typically in the order of 50 ohms unbalanced and up to 100 ohms balanced. If you think that 10 feet is inconsequential, consider that the Intel Core Two Duos have what is called a Front Side Bus, which is on the order of a few inches, and is rigorously controlled, as to line impedance and termination. It is directly involved in the marvelous performance of those devices, matching and exceeding that with which AMD competes, and AMD doesn't have a front side bus! If the FSB was not controlled we would all be either running AMD or running behind.
Think of it this way. The pulse which corresponds to, say a "one" is like a golf ball, a steady stream of golf balls heading for a target. Now, if the target is somewhat soft and thin, the ball gets through and lands on the space waiting for the signal "One" or "Zero". Now, consider a target is hard. The ball hits the target, bounces back and Uh oh!, it's heading back to the source. But wait! There is more! Another ball is heading to the target, it gets hit by the returning ball, and in this case, is a zero ball. The two cancel, and a pixel location gets the wrong info.
I have worked with transmission lines for years, both RF and digital. At Intel, I was responsible for measurements involving FSB performance on CPU to MCH (Northbridge) connections.
Since I have no recent experience with the practical notions of DVI cabling, I went to my source, who detailed it for me, far more than I have written here.
Anyway, take it for what it's worth. You can do as JJ suggests and try before you buy. And buy from a dealer that allows returns, should you decide for you, it makes no difference.
One more thing: The electronics has to terminate the cable correctly. If it doesn't, no amount of cable upgrade will improve performance!
You get what you pay for.