You can go longer if you use one of these.
You can read up about length limitations here.
As 01001010 said, you either "have it or you don't" since it's digital. I personally have a 25 footer running from my computer to my 50" plasma, and I see no loss in quality.
Intel Core i7-2600K @ 3.4GHz || GIGABYTE GA-Z68X-UD3P-B3 || Corsair Vengeance 16GB DDR3-1600 || EVGA GeForce GTX 480 || Samsung EVO 256GB SSD
my feet get cold and that gives me diarrhea sometimes - Smart_Guy