Here's a good mac site on this topic.
http://www.yale.edu/chinesemac/
My Chinese speaking developer friend was able to switch my english MacOSX in about 2 minutes. He said the windows support, unless you get a localized version of Windows, is rather poor in comparison. One of the big things is that the Mac will display better anti-aliased characters which he finds much easier to read. Also it will automatically select the correct character set when displaying asian websites.
Hope this helps.