Hmm. Mine is opposite. All dark colours are too light, so the image looks washed out. I've been able to compensate in the Nvidia control panel by setting the gamma compensation to 0.8. Maybe a different value would work for you. There are tools and test images you can use to work out a correct gamma.
It's a shame you can't do this calibration in the monitor itself, and that it isn't accurate in the first place. The setting in the Nvidia control panel doesn't seem to stay in games, but many games have their own gamma settings. I've also found a page describing a way to make it stick, though I haven't tried that yet.
http://forums.steampowered.com/forums/showthread.php?t=1051371