You can write plain text files on a mac in a format readable on windows. Mac, Unix, Windows, all use different HEX code to end the lines. Therefore a line ending on a Mac will show on Windows as an empty box. Paragraphs will show as a huge chunk of text.

With smultron, found @ smultron.sourceforge.net, you can set the editor to the line endings of your desire. Now it’s easy to exchange plain text files between a mac and an iPaq, for instance!