Windows has a couple of different font rendering systems. Chrome uses GDI, IE9 uses DirectWrite, and Firefox can use either. DirectWrite is a lot smoother, and that's most of the reason why I prefer Firefox in Windows.

The fonts on this site look worst in Win/FF. They're not great in Win/Chrome, but at least they look well matched. It looks good in OSX/Chrome. Probably because that's what it was developed in.

Protip: different browsers render fonts differently. Test your site before you release it into the wild.

Looks ugly in Firefox on OS X, but maybe it's just a bad choice of font.

http://i.imgur.com/ze1iQ.png