I suppose it depends on how you look at it. It used to be that the two main fonts were Arial and Times New Roman (and Courier New), then they switched to Calibr

I suppose it depends on how you look at it. It used to be that the two main fonts were Arial and Times New Roman (and Courier New), then they switched to Calibri and Cambria (and Consolas). At the same time, as you say, they switched Word's default from serif to sans serif (because sans serif are better for on-screen reading, and the assumption about how documents would be read had changed). I'm sure we can agree on all those facts. Whether Calibri is a replacement for Arial or Times New Roman is just a matter of what we each mean by the word "replacment" and is not interesting. I think Calibri looks extremely readable on screen (at least on Windows with ClearType, which is what it was designed for). At the end of the day it's a matter of opinion. Your article on Tahoma and Verdana was very interesting! To veer a little further off topic: I was under the impression that those fonts, or at least Verdana, was primary designed for great readibility for very short text labels in dialogue boxes, so it does make me wince when I see them used for long documents, especially printed ones.