Take a look at this cool post by Pete Brown on using fonts wisely across multiple platforms.
WPF 4 has Great Font Rendering. So, what are you waiting for? There are so many great WPF applications out there that just need these simple text options changes (which can be put into global styles) in order to go from awesome to truly friggin awesome.
WPF has gotten a lot of abuse about its font rendering over the years. While I understand why the rendering was the way it was, I'm one of the people who complained about it. WPF 4 totally changes that. It has font rendering that is as good as any native Windows application, and better than most every other developer platform. Pick good fonts (a must in any case) and set the right options to take the fuzz out of your WPF applications.