You might want to look into frontends for GNU Chess. GNU Chess is a command-line program, but many frontends exist; in fact, the Chess program that comes with OSX is just such a frontend, and so any frontend you would find on Windows would play pretty much the same way at given difficulty levels.
One example would be [url=http://www.tim-mann.org/xboard.html]WinBoard[url]. This is probably one of the "very simple 2D implementations" you were talking about, and indeed the GUI is simplistic, but underneath it's the same chess code that OSX uses.