ClearType makes text appear clearer by manipulating pixel subcomponents to smooth fonts. In Windows Vista ClearType is enabled by default and optimized for LCD displays. Along with this new change comes a handful of new fonts designed to take advantage of ClearType. Check out samples below:

If you are at a Windows XP computer right now and have not heard of the ClearType feature, you are going to love this:

1) Right-click on the desktop and choose "Properties" to access display properties
2) Click the "Display" tab and click the "Effects" button
3) The second affect listed says "Use the following method to smooth edges of screen fonts:" the options are "Standard" and "ClearType". In XP this is "Standard" by default. Pick ClearType and press OK.
4) Open a text document or web page to see the difference when it happens and then click OK to the display properties window.