The problem is the browser , not your site.
Internet Explorer 9 uses the ClearType subpixel position to render text using DirectWrite. This can lead to differences in rendering compared to other browsers and expected behavior. This can cause the text to blur a bit, as you see.
As an additional note, you should use TypeKit if you want to use non-standard fonts and render them (reasonably) well for all users. Please note that in browsers there will still be slight differences in the differences, probably at the same level as you have here.
And as Alan said, using normalize.css is a good idea.
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