I've owned and run 150' VGA cables...gone longer when using BNC component breakouts. You may see a little signal degradation, especially if you're bundling with other cables, using cheap cables with sub-par shielding, driving the video with a device that doesn't push enough signal or creating interference by crossing power cables outside of conduit or fluorescent ballasts or the like. If this is for a home, office or studio installation I'm sure you'll be fine.
Paul, go to monoprice.com, they have the best price on cables, high quality too. I used a 35' flat HDMI cable which you referenced to me about my studio pic. It is running to my main computer in another room, 35' was just barely long enough with about 1' of play on location of my computer.
I ran a 50 foot dvi cable in my wall to the projector and it did not work... I ended up finding a dvi amplifier of some form that I put on the projector end, with a small additional cable, in order for it to work... if anyone needs the info I can look at the little amp thing to find out what it was... Newegg has good prices on cables too, especially tripp lite branded stuff, and they work okay for everything else.
VGA can go a long way (can't remember the exact number right now) but you are probably safe with anything under 75' or so without an amplifier. DVI does not go far without amplification, HDMI is better but not as good as VGA. Any of them can be amplified to get more distance. I've generally used Extron amplifiers when I was doing AV installs but I know there are less expensive options out there as well.
