I found a heavy duty, triple-shielded 25' cable from a computer products website. The cable is as thick as my thumb (i.e., big). I suspect it uses oversize wire. They also sell a 50' cable. The owner of the website says he's connected two 50' cables for a "mission critical" operation at their office.
I was going to order an extra one and put DVI=>HDMI adapters on the ends to make the HDMI cable I also need. But, I decided not to be "cheap" and bought the high-end HDMI cable from RAM. Just got it yesterday, but haven't tried it yet.
All I can say is the DVI cable cost $40 and works great. I have no problems transmitting 1080i from my cable box across it. And, it looks better than a component connection -- so I'm sure there's no data loss. (Also, I agree with Bob that it should work/not work. Analog (component) cables with show degradation over long runs, digital cables while just cease to function at a point).
My RAM HDMI cable may also work, but I'm sure my STSI DVI cable is the better deal. Just looking at it provides a level of comfort that says it's well-made and well worth the price. Look here
is you want to check the STSI DVI cables out.