There are several free unicode fonts on the Internet. The one that I use and recommend is one named Bitstream Cyberbit. It covers a huge range of characters including Greek, Chinese and Japanese.
As of writing, you can download this font free of charge from:
ftp://ftp.netscape.com/pub/communicator/extras/fonts/windows/Cyberbit.ZIP
If it is no longer available, please search for ``Bitstream Cyberbit''