In recent MPC versions the colours are "normal", i.e. how they should appear (unlike previous versions were they were not vivid enough).
But now for DVDs I use WinDVD which has a little better colors, I guess it does a slight color correction.
I do not think that it is good to apply a too big change to images, as it changes how they look in the original movie. Maybe it looks better, but it is not the original...