I found an article online titled the Anatomy of Web Fonts and thought it was really interesting.
"If one aspect of design has suffered most in its transition to the Web, it is the art of typography. For years, Web typography involved little more than choosing a typeface and font size. Unstyled Times New Roman was the norm, and the integration of established typographical techniques and rules was unimagined."
"But times change. Since the adoption of CSS into mainstream Web design, we have entered a new age of Web typography. This facet of design has been opened up to the Web designer in a way that wasn't possible in the past. We now have the tools to return typography to its true role within the sphere of design."
Low contrast and simple strokes with a consistent weight and thickness, wide letter spacing, tall x-height, and wide punch (counter) width make for the most legible web fonts. Ultimately though however carefully we try and pick our fonts as designers the viewer has ultimate control. If I was posting a large body of text on my websites and I felt that my audience would more than likely print it to read it since this is easier on the eyes, I would go with a font like Helvetica that has been proven as a legible font for both web and print.
If you have a chance read the article. It is a bit elementary but the guy makes some valid point. The technical part of the article is what was most interesting.