you’re going to run into the same issue with any @font-face solution (google fonts, fontsquirrel, typekit, etc.)
the thing is older browsers on windows use windows’ font smoothing, so some fonts will look like crap. a classic example of this helvetica vs arial on windows. helvetica renders like chicken scratch and arial looks just fine.
probably getting a bit off topic, but here’s a good read on why the fonts look different based on browser/OS: http://www.joelonsoftware.com/items/2007/06/12.html