Windows has distorted the font here hasn't it? If you're rating fonts on sharpness, Windows would win here, but by any other criteria (distortion, kerning, adequate aliasing, legibility), it fails. The Windows rendering almost looks like a monospaced font. You're throwing a lot out in order to get things sharper at small sizes, and for many people, that matters far more than perceived sharpness.
Seriously? I could agree that it may not fully represent the intended font, but the entire point is that it's more legible when it sacrifices that, and I find it hard to believe that you find Windows's text to be less legible than Mac's/Ubuntu's.
i.e. I think Windows sacrifices the fontmaker's intent in order to please the reader, who couldn't care less about the fontmaker's intentions rather than the actual output (unless the reader is the fontmaker himself).
Kerning, character spacing and character shape are all designed to help legibility, and I think frankly that the Windows approach is a naive attempt to optimise one aspect of legibility at the expense of all others. So yes, I'm afraid I do disagree that it is more legible, I think it sacrifices too much, as these screenshots make clear the font is deformed so much it looks like a different font, spacing is all off, and glyphs are uneven.
This is somewhat subjective, and you might have a different opinion, but there is more than one variable in play when it comes to legibility, it doesn't just come down to how sharp the text is.
I know, I didn't mean to imply sharpness is the only factor. It's just one of several important factors.
But I couldn't care less about the font being deformed, as long as it looked better than it used to. The fact that you seem to care so much about the deformation into a different font seems to imply to me that your goal is to preserve the original font, rather than to make it look nice on the screen.
If you have the time, would you mind taking the pictures in the comment below and making a smaller bitmap that shows exactly which character(s) you think are not kerned well, and which Linux or Mac kerns better? I'm really curious what I'm not seeing.
Kerning: Look at the a in was, or the e in difference, or OS X - all of these have too much space and the difference is obvious.
Distortion: IMHO Fonts carry meaning and affect legibility, they are not just there to make text look nice on screen. Deforming a font subtracts meaning, and in some cases will make it less legible, particular an automated deformation like this.
