Here are some other "
expert" sources on the issue of the new
millennium, and each favors the view that the
third millennium of the so-called
Christian Era will begin on 1/1/01.
The Royal Observatory at Greenwich
http://www.rog.nmm.ac.uk/leaflets/new_mill.html
The (above-mentioned) US Naval Observatory
http://www.usno.navy.mil/millennium/
Scientific American magazine
http://www.sciam.com/askexpert/math/math10/math10.html
These are the fruits of a five-minute Web search. Also, see my writeup on Dionysius Exiguus for more information on the "scribe" that started all the controversy. Of course he wasn't a mathematician--hell, even the concept of negative numbers wasn't to appear in Europe for some time yet. But the idea that a "century" (from the Latin word for "one hundred") of 99 years would be somehow more acceptable to a mathematician than a system with no Year Zero is preposterous. My apologies for being rough on eponymous, but if you want to quote an expert, you should be prepared to back it up with some documentation.