Sorry but given you disabled clear type, all I can do is agree this does happen.
Did you need a discussion about how there are only so many pixels and how clear type works to make the best possible display?
This was a software solution to make the best of what pixels are there.
I've disabled Clear Type in Win 7, and now the fonts in some pages are not displayed properly (both in Fx and IE8).
* I wouldn't like to set a fixed font.
Here is an example:
This is how I get the page: