Blurry Text on Apple iMac OS X 21.5"
Both screenshots look normal, but subpixel rendering is disabled in the Pixelmator dialog.

There is a hidden preference for using a lighter text rendering style:

defaults write -g AppleFontSmoothing -int 1
sudo defaults write -g AppleFontSmoothing -int 1


The second command affects the force quit window and login screen. You have to quit and reopen applications to apply the changes.

Other than that, you can't really change the way text is rendered.