It is such a small thing, but the font rendering quality has always prevented me from enjoying Linux. I read so much while on the computer the horrible rendering and kerning just nag at me until I don't feel like reading anything else until I switch OS's.
Is it the rendering or the font choice that you don't like? I, for one, install Lucida Grande as my system font and Monaco or Menlo as my monotype font and think the design looks much fresher.
Sure, the rendering isn't 100% perfect, but with sub-pixel smoothing, I really don't mind it.
Note that font rendering differs massively between distributions. I prefer Ubuntu's softer (OS X -style) look best. Others might prefer Fedora's crisp (Windows-style) rendering.
