Most modern graphical desktops have an option to render fonts taking into account the positions of the sub-pixels on liquid crystal displays. Since these are always in the same positions relative to the pixels, one can subtly alter the horizontal position of something by changing its hue. This effectively triples the horizontal resolution, which can make for a great improvement in the readability of text.
Unfortunately, my Ubuntu desktop doesn't do this correctly - some bits of text have a yellowish fringe and some bits of text have a bluish fringe, both of which are quite distracting. The problem is that while you can alter the horizontal position of something at sub-pixel intervals, you can only alter its width by whole pixels (otherwise the hue changes don't cancel out and integrating over a region of the screen gives a yellow or cyan colour.
I've therefore had to switch my desktop to use grayscale anti-aliasing, which is a bit more blurry. Fortunately the pixels on my monitor are small enough that this doesn't bother me very much. I do prefer the font rendering that Windows does, though. While FreeType does apparently include code to support Microsoft's patented programmed hinting I can't seem to get the font rendering on Linux to look as good as it does on Windows.