The cygwin32 product is a ups product made from the Cygnus Solutions' Cygwin product, which provides a UNIX-like API and various GNU utilities on top of the Win32 API, including the "bash" shell, GNU make, the GNU C/C++ compiler, etc.
General information about the product can be found at cygnus.com
An online copy of the Cygwin User's Guide is available.
If you want to install Cygwin and the ups/upd software suite on your PC running NT for the first time, you should use the bootstrap product.
A note on upgrading your cygwin version from an existing Fermilab installation is under development