You might try the ClearType tuner at http://www.microsoft.com/typography/cleartype/tuner/step1.aspx. Note the page uses an ActiveX to do the work, so you'll probably need IE or IE Tab for FF.
Thanks to "Red M@" for that link. It's a Microsoft web site, so I used Internet Explorer instead of Firefox to run the online ClearType Tuner. It's a fairly nice web application, and Microsoft clearly has but some thought into this. (I have a problem with making users go to a web site to tune local settings, though - that doesn't make any sense.)
The problem is that the Tuner doesn't work. I get to step 2, click on RGB, then try to click Next. Nothing happens. The site is frozen at this point. So now I have no way to make fonts look less blurry. Great.
Interestingly, there's some text on this page that talks about a downloadable tool. But you're out of luck if you happen to use Vista. Even Microsoft doesn't support Vista!! Here's what Microsoft has to say:
If you experience problems download Windows XP PowerToy version of the tuner. Please note that the online tuner does not currently work with Windows Vista.