OK, since you guys are having a hard time figuring this out... this 20-pin to 24-pin adapter does not wire-up the extra 4 pins. Since a 20-pin plug will fit into a 24-pin socket anyway, this adapter isn't an adapter at all. If anything, all it gives you is an extra 5 inches (please resist the double entendre!).
Yeah, and I agree, I'd rather spend $10 on this "killer" adapter than $200 on the killerNIC.