When you don’t have the right international fonts installed you get little square boxes with four numbers in them instead of the right character when trying to view a page in Firefox. I think this also happens in IE and Opera, but I have not tested.
Anyway, the solution is to get the right fonts for your system so it can display international characters. Simply download the following from Microsoft and install (Genuine Advantage pass required):
Once installed the boxes disappear, and as a bonus .nfo files display correctly too!