Maybe you're zooming in using the Windows Photo app or something like that: open the png files in your favorite editor (I just tried with GIMP) and you'll see that the letters are pixel-perfect, unless you're upscaling them at uneven resolutions.
To give you additional support I need more info (which software are you using? how are you trying to use the fonts?), you cand send me an email with screenshots / etc if you want.