Cygwin is an OpenSource implementation of the Unix API and many GNU tools for Windows (9x, NT, 2000, etc.) It works very nicely and can be downloaded from cygwin.com, or http://sources.redhat.com/cygwin/ (I've had recent problems with the version of cygwin's setup.exe from cygwin.com.
Here is a link to all the current Codev topics that mention
Cygwin.
For details on a mainly Cygwin-based installation of TWiki on Windows, see WindowsInstallCookbook.
-- MattWilkie - 25 Oct 2001
-- RichardDonkin - 21 Apr 2002
-- ShawnMaclaga - 19 Jan 2005