50ft monitor cable

[guids]

I have an 56in lcd tv, with a vga input, and I want to hook up my computer to it, from what I read most video cards say not to go over 3 meters or so, but I find 50ft monitor cables out there, is it really that big of a deal? how much quality will I lose? I have a dual head dvi video card, and will need a vga adapter.