With Windows XP, ClearType delivers improved font display quality over traditional forms of font smoothing or anti-aliasing. ClearType improves readability on color LCD displays with a digital interface, such as those in laptops and high-quality flat panel displays. Readability on CRT screens can also be somewhat improved.
You do know the look and feel difference between a Word Document and a PDF page. Right? This is for more smooth font (Adobe-y look)! Can be configured in 4 easy steps!