Text rendering still blurry : Best font for WPF application?

You could try with the fonts that have been optimized for ClearType. Typically their names will start with a 'c':

Many, but not all, fonts that start with C and come installed with Windows Vista (Cambria, Calibri, Corbel, Candara, Consolas, etc...) have been designed to work well with WPF. In addition to these, fonts with robust outlines like Verdana, Georgia, etc… display well on computer screens.

(quoted from Text Clarity in WPF).

(image source: http://windowsclient.net/wpf/white-papers/wpftextclarity.aspx)