Torrent Client - Command line - Windows

aria2 is a command line downloader with BitTorrent support and Windows binaries available.

Most of the common command-line clients should compile under cygwin in Windows. I have rtorrent running this way on a couple of Windows machines.

Edit: another thought: I assume that Python based clients should run under Windows too if you install Python. Though off the top of my head I can't think of such a client that is actively maintained (the original "official" client was Python based, but IIRC uTurrent has replaced that).