[CentOS] Extended characters not working on CentOS

A friend of mine here at work pointed me at this web page
www.fhlcell.org where there are a lot of Chinese characters on the
page.

Interestingly enough, on my CentOS 5.2 system, with both Seamoneky
1.1.11 and Firefox 3.0, we were unable to get the characters to
display properly (they showed up as the little four number boxes
instead).

However, on his Ubuntu system, using Firefox, they displayed just
fine.  Also, I just tested it in Win XP and both Seamonkey 1.1.11 and
IE display it correctly.

What's going on?

mhr