This is a "feature" of the Windows Command Prompt Window. It uses the "DOS: United States" character set and not Unicode. é and ç are hex E9 and E7 respectively in Unicode and Windows:Western.

If you open up the Windows "Character Map" program and go to the Lucida Console font and choose the "DOS: United States" character set, you will find that the greek characters Θ and τ map to hex E9 and E7.

Solution? I'd say use cygwin. Or maybe there is a way to tweak the character set for a Command Prompt in the registry, that I do not know.

-imran