The best way to ensure copyright is to publish your code. That way, you have dated source (with file creation times or whatever) that could be used in court if someone like Microsoft tries to rip you off. Compaq had to spend millions to do a clean reverse engineering of the original IBM ROM BIOSs, because IBM published and copyrighted everything.
To me, the only downside of open source the extra disk space needed, but then the government could use some sort of CVS a la Source Forge.
I have a wiry brain/each eye a camera. Robot Tourist, by Ten Benson
