Firefox, like OpenOffice.org, bundles its own renderer instead of using the OS's renderer. That's why Ubuntu fonts look good, and Firefox fonts look blurry.

Even with msttcorefonts installed?

The problem is that it doesn't look good out of the box. I shouldn't have to hack a bunch of stuff together to get it working properly.

True - but when we start comparing it to Windows - (disable crapware, install firefox, install anti-virus, install iTunes) vs Ubuntu (install restricted-extras) then a Ubuntu setup starts looking pretty good.