Scoble and Dudley are having a debate about fonts and I can't help but think the little screenshot isn't enough to go on. For one, it's clear that Japanese fonts are not rendered using ClearType, so that's a topic for a different day. Right now I want to focus on regular Latin fonts.
I've put up a test page along with a screenshot that shows what everyday fonts look like on my Windows XP machine (with ClearType, tuned to my eyes on a Dell 2000FP, and 120 DPI fonts). I'm interested in seeing comparisons rendered on OS X, Linux, Windows with different settings, etc. Feel free to swap out fonts with ones you think look better; overall quality is what matters, not font-for-font rendering comparisons.
Note: When viewing the screenshot, make sure you have image scaling disabled. Also, if you post your own, please use PNG.