Don't feel bad mouser, my score was 33, and I thought I did a good job – although I knew it wasn't perfect, as it was quite hard for me to see much difference between adjacent colors. Flash Toy of the Week: How Well Can you Differentiate Colors?
I am sure that the problem lies in the quality of our screens, it can't be our eyes.
By the way, did you notice how even (flat) your distribution was, mouser? I am not quite sure what that means, but it is quite impressive.