Not sure I know what you mean by "clean." I use cleartype anyway (on by default in Vista/7) so most fonts look pretty clean to me.
What I don't understand is why neither IE9 nor FF4 mimic Chrome's "get rid of the wasted title bar space" when maximized.
It sucks in XP though. I always preferred Apple's font rendering to MS's, I too think it looks more clear whereas the MS AA fonts look blurry. At least on XP anyway, 7's is good. I don't know about Vista.