The best article that I have read regarding cable is this one...
I know this was testing speaker wire, but the idea is the same for interconnect cables.
The basic conclusion is there is a difference with guage and distance of a cable, but the material did not matter.
My advice is...Buy a good quality, heavy guage cable and you should be fine. When I say "good quality", I don't mean the Monster cable that is overpriced (do not waste your money). I just mean that you can probably do better than the thin little cables that come with your equipment.
Take a look at surplus stores. I was able to find some quality cables at a surplus store for $2 a piece (manufactured by RCA and marketed as "high end" and sold in stores for much more).
You should be able to find similar cables on ebay for much less as well. The 99c HDMI cable that is being mentioned in other threads is a good example.